(1967). Ulrich's international periodicals directory 1967-1968: A classified guide to a selected list of current periodicals, foreign and domestic (12th ed.). New York: R. R. Bowker.
Παραπομπή Chicago StyleUlrich's International Periodicals Directory 1967-1968: A Classified Guide to a Selected List of Current Periodicals, Foreign and Domestic. 12th ed. New York: R. R. Bowker, 1967.
Παραπομπή MLAUlrich's International Periodicals Directory 1967-1968: A Classified Guide to a Selected List of Current Periodicals, Foreign and Domestic. 12th ed. New York: R. R. Bowker, 1967.
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