Rollason, Russell G., author
Alternative Pub. Cooperative, 1981
Buku Teks
Rascati, Karen, author
Wolters Kluwer , 2014
Buku Teks
Carrison, Dan, author
AMACOM, 2005
Buku Teks
Mountjoy, Alan B., author
Hutchinson University Library, 1963
Buku Teks
edited by Hugh G.J. Aitken
Social Science Reserch Council, 1959
Buku Teks