Baumgardt, John Philip
Timber Press, 1982
Buku Teks
Hempel, Edward H., author
McGraw-Hill, 1950
Buku Teks
Onslow, Muriel Wheldale, author
Cambridge University Press, 2014
Buku Teks
Foster, Andriance S., author
D. Van Nostrand, 1949
Buku Teks
Casey, Francis, author
Macmillan, 1985
Buku Referensi