Spencer, Cornelia, author
John Day Company, 1948
Buku Teks
Singh, Anup, author
Balai Pustaka, 1950
Buku Klasik
Silalahi, Ronald MP, author
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 2010
UI - Tesis (Open)
H. Amrah Muslimin... [at al]
Alumni, 1981
Buku Teks
Mohammad Hatta, 1902-1980, author
Dewan Koperasi Indonesia, 1959
Buku Teks