William Campbell Gault's mystery/crime thrillers have just been brought out by
Prologue Books in reprints. A couple of his works are public domain
in the US via Project Gutenberg.
There's actually one currently free @
Amazon & B&N as a week-long promo in the Deals forum, and there was a really big sale on some others over the weekend.
Only some of Jim Kjelgaard's works are
public domain in the US. His entire catalogue is PD in Canada due to Life+50, though.