Leo Calvin Rosten (1964). “The Many Worlds of L*e*o R*o*s*t*e*n: Stories, Humor, Social Commentary, Travelogues, Satire, Memoirs, Profiles, and Sundry Entertainments Never Before Published; with a Special Introd., Background Notes, Revelations and Confessions, All Hand-written and Themselves Worth the Price of Admission”
Quoted in Bennett Cerf, Try and Stop Me: A Collection of Anecdotes and Stories, Mostly Humorous (1944). Although this is usually credited to Mizner, the Los Angeles Times, 17 Mar. 1941, quotes Bob Oliver: "If you steal from one man, it's plagiarism. If you steal from several, it's research."