Hutagaol, Savitra B.
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 1982
UI - Skripsi Membership
Wu, Y.C.
Amsterdam Djambatan 1950
Buku Teks
Jansen, Marius B.
Harvard University Press, 1967
Buku Teks SO
Martin, Bernard
William Heinemann, 1944
Buku Teks SO
Restarick, Henry Bond
Yale University Press , 1931
Buku Teks