compiled by Ray Prytherch
Gower, 1990
Buku Referensi
Prytherch, Ray
Gower, 1987
Buku Referensi
Harrod, Leonard Montague
England : Gower Pub, 1987,
Buku Referensi
Hampel, Clifford A., editor
Van Nostrand Reinhold, 1982
Buku Referensi
Stein, J. Stewart
Wiley, 1980
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