Casebook of the Black Widowers
 Casebook of the Black Widowers is a collection of mystery short stories by American author Isaac Asimov featuring his fictional club of mystery solvers the Black Widowers. It was first published in hardcover by Doubleday in January 1980 and in paperback by the Fawcett Crest imprint of Ballantine Books in March 1981.This book is the third of six that describe mysteries solved by the Black Widowers based on a literary dining club he belonged to known as the Trap Door Spiders.