APA Style

(Editor), L, G, L. (1978, 1995). Longman Dictionary of Contemporary English (First Edition (1978), New Edition (1995)). Harlow, Essex, England: Longman Group Ltd..

MLA Style

(Editor), Longman, Group, Ltd.. "Longman Dictionary of Contemporary English". First Edition (1978), New Edition (1995) Harlow, Essex, England: Longman Group Ltd., 1978, 1995. BOOK.