Искрен Азманов: Солунският революционен комитет. In: Българска армия. (bgarmy.eamci.bg).
google.de
google.de
Marin V. Pundeff: Bulgaria in American perspective : political and cultural issues. Columbia University Press, Boulder / New York 1994, ISBN 0-88033-295-6, S.267 (google.de – Teilausschnitt).
Macedonian Patriotic Organization: An American Symposium on the Macedonian Problem. 1941, S. 7 (google.de).
Andrea Despot: Amerikas Weg auf den Balkan. Zur Genese der Beziehungen zwischen den USA und Südosteuropa 1820–1920. Harrassowitz, 2010, ISBN 978-3-447-06188-9, S. 208 (google.de).
books.google.de
“Albert Sonnichsen, an American journalist who accompanied a Bulgarian fighting group in Macedonia during the uprisings” (Sabrina P. Ramet: Orthodox Churches and Politics in Southeastern Europe: Nationalism, Conservativism, and Intolerance. Springer International Publishing, Cham 2019, ISBN 978-3-03024139-1, S.21 (englisch, books.google.com).)
Chris Kostov: Contested Ethnic Identity. The Case of Macedonian Immigrants in Toronto, 1900–1996. Verlag: Peter Lang, 2010, ISBN 978-3-0343-0196-1, S. 118 (books.google.de).
nypl.org
archives.nypl.org
The New York Public Library: Albert Sonnichsen papers, 1874–1944. (archives.nypl.org).
