Muhammad Nida` Fadlan
Surat-surat eyang hasan maolani lengkong suntingan teks dan analisis isi = The letters of eyang hasan maolani from lengkong editing text and content analysis
Fakultas Ilmu Pengetahuan Budaya Universitas Indonesia, 2015
 UI - Tesis Membership
Said Nursi
The letters / Said Nursi
Kaynak, 1998
 Buku Teks SO
Chandra Rujianto
Meretas ideologi tekstual dalam screwtape letters
2010
 UI - Tesis Open
Ellinger, E.P.
Documentary letters of credit a comparative study/ E.P. Ellinger
University of Singapore Press, 1970
 Buku Teks SO
The collected essays, Journalism and letters of George Orwell; Volume 3
edited by Sonia Orwell and Ian Angus
Harvest Book, 1968
 Buku Teks SO