Agnew, Hugh E.
McGraw-Hill Book , 1950
Buku Teks
Agnew, Hugh E.
McGraw-Hill , 1951
Buku Teks
Wales, Hugh G.
The University of Illinois Press , 1951
Buku Teks
Clark, Fred E.
MacMillan Co., 1931
Buku Teks
McCarthy, E. Jerome, author
Irwin , 1978
Buku Teks