Eide, Arvid R., author
McGraw-Hill, Boston: McGraw-Hill,
Buku Teks
Pennock, J. Roland
Rinehart and Company, 1950
Buku Teks
Mann, Roland
McGraw-Hill , 1970
Buku Teks
Christensen, C. Roland, author
Harvard University, 1953
Buku Teks
Bainton, Roland H.
New American Library, 1950
Buku Teks