Kolchak novels by Jeff Rice + 2 new by C. J. Henderson

The 2 original kolchak novels by Jeff Rice inspired the night stalker 1970 tv show

also supposedly inspired Chris Carter to create The X-Files

after more than three decades out of print, Kolchak’s creator Jeff Rice has released the original novels, The Night Stalker and The Night Strangler are together in one volume

the 2 original can be found here and here on kindle or both together as audiobook here

the 2 by C. J. Henderson can be found here and here

there is also a short stories collection by various authors here

edit : found a new one, Kolchak: Penny Dreadful Double Feature