O`Rourke, James S., author
Prentice-Hall, 2013
Buku Teks
Greenstein, Caren E., author
Wolters Kluwer, 2011
Buku Referensi
Kaplan, A.D.H., author
Brookings Institutions, 1959
Buku Teks
Artikel Jurnal
Pagana, Kathleen D. (Kathleen Deska), author
Mosby , 1999
Buku Teks