Keller, Helen Rex
McMillan Company, 1959
Buku Referensi
Thorpe, 1994
Buku Referensi
Charles Scribner's Sons, 1989
Buku Referensi
Editedeand with an introduction by Francis Brown
Holt, Rinehart and Winston, 1969
Buku Teks
edited by Irmtraud Petersson
Lucia Queensiand Press, 1996
Buku Teks