LAY, Circuit Judge.

Defendants Boyd Gray (a/k/a Punkin), Isreal Wilson (a/k/a Big Man), and Brenda Brown appeal from their convictions for conspiracy to distribute heroin in violation of 21 U.S.C. § 846. The singular and difficult issue presented on appeal is whether the trial court erred in admitting two notebooks and their contents which a government witness read to the jury. We find no error and affirm the convictions.

The sufficiency of the evidence supporting the conspiracy conviction of each defendant is not challenged. However, a review of the facts is essential to the ruling on the controversial notebooks. The indictment recited nine overt acts involving drug sales and conversations with Drug Enforcement Agents and government informant Henderson McCoy (a/k/a Poor Boy). The overt acts alleged and proven were:

1. On November 1, 1974, unindicted co-conspirator Jerry Fleming, in a conversation with a Federal Narcotics Agent, agreed to contact Boyd Griffin Gray to arrange a purchase of two spoons of heroin by the Federal Narcotics Agent.

2. On November 1, 1974, Brenda Ann Brown had a conversation with an undercover Federal Narcotics Agent in which she agreed to contact Boyd Griffin Gray concerning the purchase of two spoons of heroin.

3. On November 1, 1974, Isreal Wilson had a conversation with an undercover Federal Narcotics Agent concerning the purchase of two spoons of heroin.

4. On November 1, 1974, Boyd Griffin Gray had a conversation with a confidential government informant concerning the purchase of two spoons of heroin.

5. On November 4, 1974, Jerry Fleming sold a quantity of heroin to an undercover Federal Narcotics Agent.

6. On November 5, 1974, Isreal Wilson had a conversation with an undercover Federal Narcotics Agent where he agreed to sell two spoons of heroin for $325.00.

7. On November 5, 1974, Jerry Fleming sold a quantity of heroin to an undercover Federal Narcotics Agent.

8. On November 7, 1974, Isreal Wilson had a conversation with an undercover Federal Narcotics Agent concerning the purchase of two spoons of heroin.

9. On November 7, 1974, Isreal Wilson had a conversation with Boyd Griffin Gray concerning the sale of heroin to the undercover Federal Narcotics Agent.

Henderson McCoy, the informant, testified that on various occasions he purchased heroin from each of the defendants and had sold heroin for them as well. McCoy described the defendants' operations, stating that he received heroin from each of the three defendants which he would sell at "a rate". He testified that the defendants ran their operation from various houses in St. Louis. These houses were on Elliott and St. Louis, Evans and Sarah, and Grand and Herbert in the City of St. Louis. The money and heroin would be passed through a hole in the door and then, according to McCoy, the transactions were usually recorded in code in a book by either "Pauncho" (an unindicted co-conspirator) or Brenda. He stated heroin was sold either in "spoons" or in capsule form called "buttons". The "house" at Grand and Herbert was an apartment run by someone known to the informant as "Jimmy".

Detective Klier of the St. Louis Police Department went to the "house" at Grand and Herbert on April 30, 1975, on information that drugs were being sold there. Detective Klier found James Shelton in the apartment. The door had a two-inch hole in it and the apartment was practically vacant except for certain small items. Klier testified that he found numerous empty red capsules in one room and syringes and two notebooks in the bedroom.

Over defendants' objections, the government introduced the notebooks and their contents. The government urged in the trial court that although the notebooks were hearsay, they were admissible even though the author was unknown because they were: 1) declarations against interest; and 2) admissible under the co-conspirator rule. The trial court overruled defendants' objections.

Detective Klier was allowed to read all the contents of the notebooks to the jury. The notations specifically identified "Brenda" and "Punkin" (Boyd Gray's nickname) as taking drugs and money. Defendant Wilson was not mentioned in the notebook.

The defendants presented no evidence, relying on their motions for acquittal at the end of the government's evidence. The jury returned verdicts of guilty.

The defendants argue that no proper foundation has been laid for the notebooks, since the identity of the writer or writers was not shown. Defendants further urge that the co-conspirator rule is not applicable since there is no independent evidence that the declarant was part of the conspiracy.

Initially, we find sufficient evidence to show prima facie authenticity or genuineness of the notebooks. Moreover, assuming, without deciding that there was not sufficient proof to invoke the co-conspirator rule, we find the notebooks were nonetheless admissible as circumstantial evidence, not as an exception to the hearsay rule, but because they were not hearsay at all.

Authentication.

The entries in the notebooks are hand printed by one or more persons. The government represents that it does not know the identity of the author.

Rule 901 of the Federal Rules of Evidence provides:

(a) General provision. The requirement of authentication or identification as a condition precedent to admissibility is satisfied by evidence sufficient to support a finding that the matter in question is what its proponent claims.

(b) Illustrations. By way of illustration only, and not by way of limitation, the following are examples of authentication or identification conforming with the requirements of this rule:

. . . . .

(4) Distinctive characteristics and the like. Appearance, contents, substance, internal patterns, or other distinctive characteristics, taken in conjunction with circumstances.

Under this rule, the contents of a writing may be used to aid in determining the identity of the declarant. The primary concern in relying on the contents of an instrument to prove its authenticity is the danger of forgery or substitution of a fraudulent document. However, as has been authoritatively explained:

For this principle to operate the [writing] must deal with a matter sufficiently obscure or particularly within the knowledge of the persons corresponding so that the contents of the [writing] were not a matter of common knowledge.

The evidential hypothesis in the authentication step is this: only those who knew the details in the [writing] could have written it; if the purported writer can be shown to have probably known the details and if no other person is likely to have known them when the [writing] was written, it is likely that he wrote it. The force of the inference decreases as the number of people who know the details and may have written the [writing] increases. Moreover, if there is a serious question of forgery, the inference is subject to being rebutted by the possibility that the details were added by someone to give an air of verity to the document rather than by the purported author who obtained the information in the usual way.

5 J. Weinstein M. Berger, Weinstein's Evidence ¶ 901(b)(4)[01], at 46.

It is well settled that genuineness of a writing can be established by circumstantial proof without resort to the handwriting or typewriting. Where the writings are such that only those persons acquainted with the particular transactions involved could have written them, the authenticity of the evidence is considered more reliable.

Under these principles, we find the contents of these notebooks refer to activities (in this case, drug trafficking) and are characterized by a code of which only someone connected with the transactions would have known. The writer uses nicknames of individuals and the code term "buttons" which the informant had testified were heroin capsules. The writer was obviously familiar with the procedures used by the defendants in their drug operations. Although the precise identity of the declarant is unknown, we think there was at least a prima facie showing that the declarant was a member of the drug conspiracy charged in the indictment.

Moreover, there is other evidence which corroborates the authenticity of the notebooks. The books were found in an apartment which the informant said both "Punkin" and Brenda frequented, and in which drugs were sold. The apartment had an unusual hole in its door fitting the informant's description and a known co-conspirator was found there at the time of the raid. The informant further testified that the defendants' drug transactions were recorded in notebooks. This evidence in our view provides a prima facie showing of authenticity of the notebooks. This showing could have been, but was not, countered by any evidence from defendants that the documents were forged or otherwise not what the government claimed.

Hearsay.

Notwithstanding the showing of relevance and authenticity the notebooks must still be excluded if they are hearsay. We find that the notebooks were not hearsay since they were not offered to prove the truth of the facts asserted therein. Instead, they were admissible as circumstantial evidence (a) to show the character and use of the place where the notebooks were found and (b) to corroborate the informant's testimony. See generally, 6 J. Wigmore, Evidence § 1766, at 180 (3d ed. 1940).

The basic definition of hearsay is:

. . . a statement, other than one made by the declarant while testifying at the trial or hearing, offered in evidence to prove the truth of the matter asserted.

Fed.R.Evid. 801(c).

In the present case, the assertions in the notebooks were not material to any of the overt acts supporting the conspiracy. The overt acts were independently established. Whether Brenda or Punkin delivered, bought or sold a specified amount of "buttons" on any specific date was not part of the government's burden of proof. Thus, the truth of these statements in the notebook was not at issue in the case. The evidence, however, did tend to show that the apartment was being used for drug trafficking.

Thus, we view the declarations in the notebooks as utterances, used circumstantially, giving rise to the indirect inference that the apartment was the scene of drug sales and drug related activity. See 6 J. Wigmore, Evidence § 1766 (3d ed. 1940); McCormick's Handbook of the Law of Evidence § 249, at 589 (E. Cleary, ed. 1972). See also United States v. Pasha, 332 F.2d 193, 196-97 (7th Cir.), cert. denied, 379 U.S. 839, 85 S.Ct. 75, 13 L.Ed.2d 45 (1964); Armstrong v. United States, 327 F.2d 189, 197 (9th Cir. 1964); Reynolds v. United States, 225 F.2d 123, 131-32, (5th Cir.), cert. denied, 350 U.S. 914, 76 S.Ct. 197, 100 L.Ed. 801 (1955).

Furthermore, as the government contended at trial, the books, the entries made and the codes used were as described previously by the informant. Therefore, the existence of the notebooks and the fact of these entries served to corroborate his testimony as to the manner in which the defendants carried on their business. It is the fact that the statements were written, and not the truth of the statements, which was relevant.

We anticipate the contention that the government may have misused the statements in closing argument under the co-conspirator rule as evidencing truth of the statements in the notebooks. However, the government's argument must be taken as a whole, and it is significant that the United States Attorney later told the jury in his closing statement:

The question is not whether they sold any to Federal officers or even if they sold any to anybody else, the question is was there an agreement that they would [have] if [they] had the opportunity to sell narcotics and was one overt act made — at least one overt act made in the furtherance of that conspiracy.

Transcript at 246.

A final consideration is whether the evidence should have been excluded as too prejudicial even if otherwise admissible. In our view, the fact that Brenda and Punkin are mentioned in the book as making sales is merely cumulative to other direct proof by McCoy as to their dealing in drugs on other specific occasions. The fundamental issue was the existence of a conspiracy vel non. This issue was properly argued by the government and instructed upon by the trial court. The notebooks were sufficiently authenticated. We hold their evidential value outweighed any prejudice to the defendants.

Judgments are affirmed.