Call of Cthulhu (d20 Edition Horror Roleplaying, WotC), by Monte Cook, John Tynes
Call of Cthulhu Gamemasters Pack: d20, Horror Roleplaying, 8801, by Dustin Wright,Aaron Rosenberg
Cthulhu Now: Modern Adventures and Background for Call of Cthulhu Roleplaying/3307, by Petersen,Okamoto, Jeff,Herber, Keith,Corless, Peter,Barton, William A.
Investigator's Companion vol. 2 (Call of Cthulhu Horror Roleplaying, 1920s, #2346), by Herber, Keith, Ross, Kevin A., Rucka, Greg, O'Connell, Gary