Drennan, Robert E., The Algonquin Wits, Replica Books, 2000.

As a member of the famous Algonquin Round Table, a group of literary wits who met at the Algonquin Hotel in New York in the 1920s and 30s, Sherwood was engaged in intense intellectual competition.

Fehrenbacher, Don E., ed., Abraham Lincoln: Speeches and Writings, 1832-1858, Library of America, 1989.

The Library of America editions are painstakingly researched, checked for authenticity and thoroughness. This edition covers the same years as the play and gives Lincoln's own words to compare to Sherwood's portrayal.

Holzer, Harold, ed., The Lincoln-Douglas Debates: The First Complete, UnexpurgatedText, HarperCollins, 1993.

Edited and introduced by Harold Holzer, one of the leading historians in the field of Lincoln studies, this text gives a sense of drama that is like that of the play.

Smith, Wendy, Real Life Drama: The Group Theatre and America, 1931-1940, Grove Press, 1992.

The Playwrights Company...