edited by Edward B. Esphansade, Joel L. Morrison
Rand McNally & Co, 1966-1978
Buku Referensi
The George F. Cram, 1952
Buku Referensi
George Philip & O'Neil, 1981
Buku Referensi
Allen, John L., author
McGraw-Hill, 2004
Buku Teks
George Phillip, 1981
Buku Referensi