Macmillan Information, 1972
Buku Referensi
Macmillan Information, 1972
Buku Referensi
edited by Max M. Russell
Macmillan, 1973
Buku Referensi
Severinghaus, Aura E.
McGraw-Hill , 1953
Buku Teks
Fine, Benjamin
Barron's Educational Series, 1966
Buku Referensi