Reviews : A New Life of Anton Chekhov. By Ronald Hingley. London : Oxford University Press, 1976. xx + 358 pp.  8.75. Anton Chekhov's Life and Thought : Selected Letters and Commentary. Translated from the Russian by Michael Henry Heim in collaboration with Simon Karlinsky. Selection, commentary and introduction by Simon Karlinsky. Berkeley, Los Angeles, London : University of California Press, 1975. xiv + 494 pp. $6.95 (paperback). Letters of Anton Chekhov. Selected and edited by Avrahm Yarmolinsky. New York : The Viking Press, 1973. xxi + 490 pp. $12.50