Advanced Dungeons & Dragons, 2nd Edition is a 20-book series with 20 primary works first released in 1989 with contributions by David Zeb Cook, Aaron Allston, Grant Boucher, Arthur Collins, Troy Christensen, Rick Swan, Jeff Grubb, John Nephew, Steve Winter, Ed Greenwood, Walter M. Baas, Anthony Herring, Julia Martin, Steven Schend, J. Robert King, Tim Beach, Karen Boomgarden, Bill Slavicsek, Skip Williams, Wolfgang Baur, Lester W. Smith, Bruce Nesmith, Richard Baker, Steve Kurtz, TSR Inc. Staff, and John Terra.