Phillips, Ralph W.
Livestock of china / Ralph W. Phillips
United states Government Printing Office, 1945
 Buku Teks
Tyler, Ralph W.
Basic principles of curriculum and instruction / Ralph W. Tyler
University of Chicago, 1949
 Buku Teks
Byrns, Ralph T
Exploring economics/ Ralph T. Byrns, Gerald W. Stone
Scott Foresman, 1984
 Buku Teks
Byrns, Ralph T.
Economics/ Ralph T. Byrns, Gerald W. Stone
Illinois, 1984
 Buku Teks
The Random House American everyday dictionary
edited by Jess Stein
Random House, 1961
 Buku Referensi