歐甘字母顯然是從一種基礎字母演變而成,有學者更指出它只是那種字母的密碼。大部分學者認為基礎字母是當時盛行的拉丁字母,也有人認為是古弗薩克文(Elder Futhark)或希臘字母。如果歐甘字母的起源是盧恩字母[5],便能解釋在愛爾蘭語中沒有功能的字母 H 和 Z 存在的原因,以及拉丁文和希臘文中沒有的變異體字母 U 和 W ,但盧恩字母當時在歐洲大陸(Continental Europe)傳播不廣泛,作為基礎字母的可能性低於拉丁字母。
^Forsyth, K.; "Abstract: The Three Writing Systems of the Picts." in Black et al. Celtic Connections: Proceedings of the Tenth International Congress of Celtic Studies, Vol. 1. East Linton: Tuckwell Press (1999), p. 508
^Richard A V Cox, The Language of the Ogam Inscriptions of Scotland, Dept. of Celtic, Aberdeen University ISBN 0-9523911-3-9[1][永久失效連結]
^The New Companion to the Literature of Wales, by Meic Stephens, page 540.
^ Carney, J "The Invention of the Ogam Cipher" 'Ériu' 22, pp 62 -3, 1975; MacNeill, E. "Archaisms in the Ogham Inscriptions", 'Proceedings of the Royal Irish Academy' 39, pp 33-53, Dublin
^ McManus, 'Ibid', p11, 1991; Vendryes 'L'écriture ogamique et ses origines' Études Celtiques, 4, pp110- 113, 1931; Thurneysen, 'Zum ogam' Beiträge zur Geschichte der deutschen Sprache und Literatur, pp196-7, 1937
其他資料
Carney, James. The Invention of the Ogam Cipher 'Ériu' 22, 1975, pp 62 –3, Dublin: Royal Irish Academy
Forsyth, Katherine. The Ogham Inscriptions of Scotland: An Edited Corpus, PhD Dissertation, Harvard University (Ann Arbor: UMI, 1996). OCLC 48938210
Gippert, Jost; Hlaváček, Ivan; Homolka, Jaromír. Ogam. Eine frühe keltische Schrifterfindung, Praha: Charles University, 1992. ISBN 80-901489-3-X OCLC 39570484
Macalister, Robert A.S. The Secret Languages of Ireland, pp27 – 36, Cambridge University Press, 1937
Macalister, Robert A.S. Corpus inscriptionum insularum celticarum. First edition. Dublin: Stationery Office, 1945-1949. OCLC 71392234
McManus, Damian. Ogam: Archaizing, Orthography and the Authenticity of the Manuscript Key to the Alphabet, Ériu 37, 1988, 1-31. Dublin: Royal Irish Academy. OCLC 56088345
McManus, Damian. A Guide to Ogam, Maynooth 1991. ISBN 1-870684-17-6 OCLC 24181838
MacNeill, Eoin. Archaisms in the Ogham Inscriptions, 'Proceedings of the Royal Irish Academy' 39, pp 33–53, Dublin
Raftery, Barry. A Late Ogham Inscription from Co. Tipperary, Journal of the Royal Society of Antiquaries of Ireland 99, 1969. ISSN 0035-9106 OCLC 6906544
Swift, C. Ogam Stones and the Earliest Irish Christians, Maynooth: Dept. of Old and Middle Irish, St. Patrick's College, 1997. ISBN 0-901519-98-7 OCLC 37398935
Ranke-Graves, Robert von. Die Weisse Göttin: Sprache des Mythos (The White Goddess), ISBN 978-3-499-55416-2 OCLC 52100148, several re-editions, but rarely available. Editions available in German and English.
Sims-Williams, Patrick. The Celtic Inscriptions of Britain: Phonology and Chronology, c. 400—1200. (Publications of the Philological Society 37) Oxford : Blackwell Publishing, 2003. ISBN 1-4051-0903-3
Thurneysen, Zum ogam Beiträge zur Geschichte der deutschen Sprache und Literatur, pp196–7, 1937
Vendryes L'écriture ogamique et ses origines Études Celtiques, 4, 1931, pp110– 113,