Remember that not all indexes are electronic format. The reviews you are seeking may be in a print compilation, or in a print index to the literature:
American Drama Criticism (O’Neill PS332 .A63)
Critical Survey of Drama [Magill] 6 vols. (O'Neill Reference PN1625 .C74)
European Drama Criticism, 1900-1975 (O’Neill Stacks PN1721 .P35 1977)
Guide to Critical Reviews. 3rd edition (O’Neill Stacks PN2266.S26)
Modern Drama Scholarship and Criticism 1981-1990
(O'Neill Stacks PN1851 .C372 1997)
New York Times Theatre Reviews (1870-2000) (O’Neill Stacks PN2266 .N48)
Selected Theatre Criticism (O’Neill Stacks PN2277 .N5S44)
Scene from Act 3 of the first run Moscow Art Theatre production
