Trewartha, Glenn T., author
McGraw-Hill, 1967
Buku Teks
edited by Philip L. Wagner and Marvin W. Mikesell
University of Chicago Press, 1962
Buku Teks
edited by Philip L. Wagner, Marvin W. Mikesell
University of Chicago Press, 1962
Buku Referensi
Warf, Barney, editor
Springer, 2012
eBooks
Crang, Mike, author
Routledge, 1998
Buku Teks