Star Trek: The Lost Years
The Lost Years is a four-book Pocket TOS series, published by Pocket Books between  and . It tells the stories of the  characters in the years between the end of the five-year mission and the events of . The concept was derived by Robert Greenberger, and the series was originally intended as a trilogy, starting with a "Giant" novel by J.M. Dillard.

Novels 
 TOS: The Lost Years
 TOS #54: A Flag Full of Stars
 TOS #70: Traitor Winds
 TOS #73: Recovery

The War Virus 
The War Virus was originally announced as the third book in the trilogy, alongside The Lost Years and A Flag Full of Stars (The Lost Years, Acknowledgments). The novel was to be written by Irene Kress. It was never released, with later Pocket Books editor John Ordover noting that the novel "didn't work out for reasons I can't really get into". 

de:Verlorene Jahre
Lost Years, The