Henle, Paul
Sprache, denken, kultur herausgegeben / von Paul Henle
Suhrkamp, 1975
Buku Teks SO
Kosakata dasar Swadesh di Kabupaten Belu, Ngada, Sumba Barat, Sumba Timur, dan Timor Tengah Utara / Tim penyusun, Buha Aritonang...[et.al]
Departemen Pendidikan dan Kebudayaan, 2002
Buku Teks SO
Pauwels, Anne
Language maintenance and shift
NY Cambridge University Press, 2016
Buku Teks SO
Stewart, Mark Alan
GRE CAT Answers to the Real Essay Questions, 2nd edition (Arco GRE Answers to the Real Essay Questions)
Thomson, 2003
Buku Teks SO
Barr, Donald F.
Languages of Central Sulawesi checklist, preliminary classification, language maps, wordlists/ Donald F. Barr, Sharon G. Barr
Hasanuddin University, 1979
Buku Teks SO