Buku Teks
edited by Philip Ward
Clarendon Press, 1978
Buku Referensi
Rio, Angel del
Holt, Rinehart and Winston, Inc., 1961
Buku Teks
Unamuno, Miguel de, 1864-1936
Gateway Editions; distributed by H. Regnery Co, 1956
Buku Teks
Brenan, Gerald
At The University Press, 1951
Buku Teks