David Wells perfect game: Yankee pitcher makes history in 1998 - Sports Illustrated Vault
Yankees' Domingo German throws first perfect game since 2012, Baseball News
Yankees' Domingo German fires perfect game vs. A's
Remembering David Cone's perfect game for NY Yankees, 20 years later
15 years ago today: David Wells' perfect game - Sports Illustrated
Oral history of David Cone's perfect game
David Cone has nothing but praise for Domingo German's perfect game
David Cone, Baseball Wiki
David Cone was perfect on this day in 1999 - Pinstripe Alley
Review: Cone's perfect game — 20 years ago — among memories in his new book - The San Diego Union-Tribune