Osol, Arthur, 1905-1988
J. B. Lippincott Company, 1960
Buku Referensi
Stuart, Graham Henry, 1887-
Appleton-Century-Crofts, 1955
Buku Teks
Washington U.S. Department of Health, Education, and Welfare 1955
Buku Teks
United States Information Agency, 1987
Buku Teks
Board of Trusless, 1960
Buku Referensi