Anton Chekhov Quotes about Sleep

Anton Chekhov (2013). “Delphi Complete Works of Anton Chekhov (Illustrated)”, p.1226, Delphi Classics
Letter to A.S. Suvorin, December 9, 1890.
Anton Chekhov's letter to A.S. Suvorin, December 3, 1892.
Anton Chekhov (2015). “Greatest Works of Anton Chekhov: Plays, Short Stories, Novel and A Biography (Including The Steppe, Ward No. 6, Uncle Vanya, The Cherry Orchard, Three Sisters, On Trial, The Darling, The Bet, Vanka, After the Theatre and many more)”, p.575, e-artnow