* UFOs: Operation Trojan Horse: This book, written with Phillip Corso, claims that the US government has been in possession of alien technology since the 1940s and has been using it for military purposes.
* The Day After Roswell: This book details Knaus's investigations into the alleged Roswell incident, claiming that the US military recovered alien bodies and technology.
* Alien Contact: Knaus explores the history of UFO sightings and alleged alien encounters, offering his own theories and interpretations.
He has also written other books on related topics, such as:
* The Secret of the Stars: This book discusses Knaus's beliefs about the origins of extraterrestrial life and its potential impact on humanity.
* The UFO Cover-Up: Knaus delves into the alleged government conspiracy to hide the truth about UFOs from the public.
While Knaus's work is popular among UFO enthusiasts, it is often criticized by skeptics and scientists for lack of evidence and reliance on unsubstantiated claims. However, his books remain influential in UFO lore and continue to spark debate and intrigue.