12. Erich von Daniken letter to Mr. Blumenschein, editor at Stem magazine, Hamburg, September 17,1972. From the author’s archive (Archive No. 0238/ECON documentation).
13. Dr. Gerardo Pena Matheus letter to Erich von Daniken, September 12,
1972. From the author’s archive (Archive No. 0238/ECON documentation).
14. Pia Buob (EigenvasenstraBe 14) letter to Erich von Daniken, October 22, 1972. From the author’s archive.
15. Erwin Barth von Wehrenalp (ECON Verlag, Diisseldorf) letter to Professor UdoOberem (University of Bonn), September27,1972. From the author’s archive (Archive No. 0238/ECON documentation).
16. Udo Oberem letter to Erwin Barth von Wehrenalp, October 12, 1972. From the author’s archive (Archive No. 0238/ECON documentation).
17. Erwin Barth von Wehrenalp letter to Ramon Burneo, October 6, 1972. From the author’s archive (Archive No. 0238/ECON documentation).
18. Ramon Burneo letter to Erwin Barth von Wehrenalp, October 18,
1972. From the author’s archive (Archive No. 0238/ECON documentation).
19. Erich von Daniken letter to Dr. Pena, November 11, 1972. From the author’s archive (Archive No. 0238/ECON documentation).
20. Erich von Daniken letter to Dr. Pena, December 29, 1972. From the author’s archive (Archive No. 0238/ECON documentation).
21. Erich von Daniken letter to Erwin Barth von Wehrenalp, January 7,
1973. From the author’s archive (Archive No. 0238/ECON documentation).
22. Dr. Gerardo Pena Matheus letter to Erich von Daniken, January 26,
1973. From the author’s archive (Archive No. 0238/ECON documentation).
23. Document of the members of the «Expedicion 1969». Signed by all participants. From the author’s archive (Archive No. 0232).
24. Erich von Daniken letter to Dr. Pena, February 1, 1973. From the author’s archive (Archive No. 0238/ECON documentation).
25. James B. Mobley (Media Associates Company, Los Angeles, California) letter to Erich von Daniken, March 5, 1973. From the author’s archive (Archive No. 0238/ECON documentation).
26. Erich von Daniken letter to Dr. Pena, March 16, 1973. From the author’s archive (Archive No. 0238/ECON documentation).
27. Thompson, Ron. «The Mystery of Ecuador’s Secret Treasure». Newspaper article from June 17, 1973. From the author’s archive (Archive No. 0095).
28. «Juan Moricz realizaria una nueva expedicion».
29. «Pueden tildarme de loco» (and various other articles from the author’s archive; Archive No. 02699).
30. Erich von Daniken letter to Neil Armstrong (Cincinnati), February 18, 1977. From the author’s archive (Archive No. 01752).