Great books of the western world; Vol. XIX
edited by Mortimer J. Adler
Encyclopedia Britanica, 1990
 Buku Referensi
Great books of the western world; Vol. XXII
edited by Mortimer J. Adler
Encyclopedia Britanica, 1990
 Buku Referensi
Great books of the western world; Vol. XXIII
edited by Mortimer J. Adler
Encyclopedia Britanica, 1990
 Buku Referensi
Palmer, Joel
Journal of travels over the Rocky Mountains
Ann Arbor University Microfilms 1966
 Buku Teks
Lan - Ong
Thu'o'ng Kinh Ky-Su (Relation d'un voyage a'la capitale)
Paris: Ecole Francaise, 1972
 Buku Teks