Abd Allah ibn Saba' (English Wikipedia)

Al-Samarrai, Qasim (2000), "Sayf ibn ʿUmar and ibn Sabaʾ: A new approach", in Tudor Parfitt (ed.), Israel and Ishmael: studies in Muslim-Jewish relations, Palgrave Macmillan, pp. 52–58, ISBN 978-0-312-22228-4
inauthor:"أبي محمد الحسن بن موسى النوبختي". pp. 19–20.^{[full citation needed]}
History of the Jews: From the Roman Empire to the Early Medieval ..., Volume 2 By Simon Dubnov page 330 where it talks about Abdala Ben Saba [1]
Jewish Literature from the Eighth to the Eighteenth Century: With an ... By Moritz Steinschneider, William Spottiswoode page 59 [2]
"history of the jews". Associated University Presse. 1987 – via Google Books.
There is also other non Muslim literature from near that time like The Chronography of Bar Hebraeus By Bar Hebraeus [3] Archived 2013-10-24 at the Wayback Machine

brill.com

Landau-Tasseron, Ella (January 1990). "Sayf Ibn 'Umar in Medieval and Modern Scholarship". Der Islam. 67: 1–26. doi:10.1515/islm.1990.67.1.1. ISSN 1613-0928. S2CID 164155720. But Linda D. Lau and A. R. Armush, in what seem to be independent studies, reached the conclusion that Sayf's explanation is not only the sole existing one, but is also governed by inner logic so that there is no reason to reject it.
Anthony, Sean W. (2011). "The Legend of ʿAbdallāh Ibn Sabaʾ and the Date of Umm Al-Kitāb". Journal of the Royal Asiatic Society. (Third Series). 21 (1): 1–30. doi:10.1017/S135618631000060X. S2CID 163022275. JSTOR

Halm, Heinz (December 15, 2001). "ḠOLĀT". In Ehsan Yarshater (ed.). Encyclopedia Iranica (Online ed.). Retrieved October 20, 2011.

Anthony, Sean W. (2011). "The Legend of ʿAbdallāh Ibn Sabaʾ and the Date of Umm Al-Kitāb". Journal of the Royal Asiatic Society. (Third Series). 21 (1): 1–30. doi:10.1017/S135618631000060X. S2CID 163022275. JSTOR

Landau-Tasseron, Ella (January 1990). "Sayf Ibn 'Umar in Medieval and Modern Scholarship". Der Islam. 67: 1–26. doi:10.1515/islm.1990.67.1.1. ISSN 1613-0928. S2CID 164155720. But Linda D. Lau and A. R. Armush, in what seem to be independent studies, reached the conclusion that Sayf's explanation is not only the sole existing one, but is also governed by inner logic so that there is no reason to reject it.
Anthony, Sean W. (2011). "The Legend of ʿAbdallāh Ibn Sabaʾ and the Date of Umm Al-Kitāb". Journal of the Royal Asiatic Society. (Third Series). 21 (1): 1–30. doi:10.1017/S135618631000060X. S2CID 163022275. JSTOR

"Refuting the defence card of Abdullah Ibn Saba". Archived from the original on 2016-01-07. Retrieved 2016-11-20.
There is also other non Muslim literature from near that time like The Chronography of Bar Hebraeus By Bar Hebraeus [3] Archived 2013-10-24 at the Wayback Machine

Hodgson, M. G. S. (1960). "ʿAbd Allāh ibn Sabaʾ". In Gibb, H. A. R.; Kramers, J. H.; Lévi-Provençal, E.; Schacht, J.; Lewis, B. & Pellat, Ch. (eds.). The Encyclopaedia of Islam, Second Edition. Volume I: A–B. Leiden: E. J. Brill. p. 51. OCLC 495469456.
Landau-Tasseron, Ella (January 1990). "Sayf Ibn 'Umar in Medieval and Modern Scholarship". Der Islam. 67: 1–26. doi:10.1515/islm.1990.67.1.1. ISSN 1613-0928. S2CID 164155720. But Linda D. Lau and A. R. Armush, in what seem to be independent studies, reached the conclusion that Sayf's explanation is not only the sole existing one, but is also governed by inner logic so that there is no reason to reject it.