Buku Teks
edited by Philip Ward
Clarendon Press, 1978
Buku Referensi
Kefala, Antigone
Wild & Woolley, 1975
Buku Teks
Rio, Angel del
Holt, Rinehart and Winston, Inc., 1961
Buku Teks
Unamuno, Miguel de
Gateway Editions; distributed by H. Regnery Co, 1956
Buku Teks