Inspiration for Lazar using element 115 in his story?
The alien spacecraft in Bob Lazar's story is claimed by him to use element 115. Where did he get this idea? Possibly from a 1989 Scientific American article that mentioned it, but perhaps from episode 32 of "Lost in Space" (Season 2) from 1966. The episode, titled "The Ghost Planet", has a base dug into the side of a mountain (just like his "S4" at Papoose Lake) with "Gate 115" adorning the entry. The show also features a flying saucer-type transport used by the protagonists. Thanks to Amy Collins for this possible lead.
https://en.wikipedia.org/wiki/List_of_Lost_in_Space_episodes#Season_2_(1966%E2%80%9367)
Ultra-terrestrials: not a new idea
From page 148 of the 1988 printing of "The UFO Phenomenon" (Time-Life Editors; ISBN: 0-8094-6324-5), part of the "Mysteries of the Unknown" series of Time-Life Books. Far from being the only hypothesis for UFOs, the extraterrestrial hypothesis (ETH) for interplanetary visitors has competed for decades with the inter-dimensional hypothesis (IDH). Denizens of this other dimension or universe are often called "ultra-terrestrials" in UFO lore. Some proponents of this hypothesis have arguably become even more radicalized and unconventional than many of the advocates for the ETH, especially given the proposed links between the IDH and the nature of consciousness - a topic that is closely tied to much of the discourse in "ufology" and which dovetails with challenges to material science through the use of the mysteries of consciousness as a wedge with which to smuggle in spiritualism and other woo.
Inspiration for Lazar's "9 flying saucers at S4"?
It is a certainty that Lazar, to put it politely, borrowed tropes and themes from UFO TV specials and movies that he then assimilated into his own story. The 1959 horror/sci-fi film "Plan 9 from Outer Space" about space aliens resurrecting the dead to act as slaves, might well have served as an inspiration for Lazar's decision to "recount" that he saw 9 extraterrestrial craft at "Area S4". Of course, we can never know this for sure, and the reference to the number 9 could have been inspired from any of a plethora of other media items, but some of Lazar's plagiarisms are so insultingly hokey that we are free to speculate until he comes clean. The film can be found here in full: https://youtu.be/Ln7WF78PolA
What Lazar didn't predict
This is from the March 1955 issue of "Fantastic Universe Science Fiction" magazine (ISBN: 6-211-45503-8). Many people seem to believe that Bob Lazar "predicted" the tipped-on-their-side motion of fly saucers that is supposedly seen in the US Navy "GIMBAL" footage. In fact, this configuration was a dime a dozen well before Lazar ever yapped about flying saucers. The artwork on this magazine is just one example of many depictions of a flying saucer tilted on its side. Here is another one from the 1980 TV special "UFO Syndrome".
Image credit: Abebooks.com
A Pteranodon not from the planet "Neber"
From page 129 of the 1981 edition of "Life Before Man" by Zdeněk Špinar and illustrated by Zdeněk Burian (Cresent Books. ISBN: 0-517-34722-9). The Pteranodon in the upper middle of the picture was plagiarized by Wendelle Stevens and Eduard "Billy" Meier circa 1975 to be passed off as a photograph of an actual creature on the planet "Neber", which Meier claims to have visited on his voyages aboard a "Plajeran" spacecraft. It was included in Steven's unpublished Preliminary Investigation Report manuscript. It is only one of many plagiarized images that the Meier cult used or planned to use to promote the mythos surrounding its messiah and "prophet" Eduard "Billy" Meier.
Groom Lake base (Area 51) mentioned in 1985
From page 48 of the 1985 book "Techniques and Equipment of Electronic Warfare" by Doug Richardson (Prentice Hall Press. ISBN: 0-668-06497-8). Note the reference to the "Groom Lake facility" - years before the fraud Bob Lazar (of "S4" and "alien technology reverse engineering" fame) ever talked about Area 51 (which was mentioned by that name in the 1988 TV special "UFO Cover-Up? Live", the year before Lazar came out as "Dennis"). The "F-19" was actually the F-117 stealth "fighter" (actually a tactical and strategic bomber). Note that this book erroneously states that Nellis AFB is in California; it is actually in Nevada. Thanks to a tight government blockade on information about the F-117, Bill Gunston's speculative sketches of what it might look like were way off the mark. Also, the designation "Aurora" had been doing the rounds, and had variously been suggested to be the "F-19" itself and, somewhat more recently, a hypersonic reconnaissance plane to replace the SR-71.