Lnge, Oscar
Warsawa Polonia Publishing House 1957
Buku Teks
Ebenstein, William, author
Prentice-Hall, 1954
Buku Teks
London : Central Books Ltd
Majalah, Jurnal, Buletin
Willimott, Andy, author
Oxford University Press, 2017
eBooks
Tsedenbal, Y.
Political Literatur Publishing House, 1967
Buku Teks