Holland, Lorien, author
Periplus Editions , 2007
Buku Referensi
Raymer, Robert, author
Editions Didier Millet, 2011
Buku Referensi
APA Publications , 2007
Buku Referensi
edited by Gerald W. Whitted
Pan American World Airways, 1971
Buku Teks
edited by Gerald W. Whitted
Pan American Airways, 1963
Buku Teks