Christie, Agatha, 1890-1976
Why didn't they ask evans? : pembunuhan di balik kabut
Gramedia Pustaka Utama, 2018
 Buku Teks SO
McCoy, Charles W.
Why didn't i think of that ? : memikirkan yang tak terpikirkan dan meraih puncak kreativitas
Prentice-Hall, 2004
 Buku Teks
Daya Tripanosida Suramin terhadap Trypanosoma evansi
 Artikel Jurnal
Fink, Arlene
How to ask survey questions
Thousand Oaks : SAGE PUBLIKATION, 2003,
 Buku Referensi
Bracken, Peg
I didn't come here to argue / Peg Bracken
Fawcett Publications, 1969
 Buku Teks SO