John Fawcett, editor
World Vision International, 2003
Buku Teks SO
edited by John Fawcett
World Vision, 2003
Buku Teks
Lunn, Hugh Duncan
University of Queendsland Press, 1978
Buku Teks
edited by Alexander L. Eastman, David H. Rosenbaum, Erwin R. Thal
Mosby Elsevier, 2009
Buku Referensi
Klepko, V.
Foreign Languages Publishing House, 1964
Buku Teks SO