Al-Attas, Syed Muhammad Naguib
Kuala Lumpur : University of Malay Press, 1970.
Buku Teks
Collins, John E. (John Edward), author
Rowman & Littlefield, 1991
Buku Teks
Khan, Hazrat Inayat
The Sufi International Headquarter's, 1956
Buku Teks
Suzuki, Daisetz Teitaro, 1870-1966, author
Harper, 1957
Buku Teks
Mann, Thomas, author
Vintage International , 1995
Buku Teks