Tolong jelaskan mengenai Huruf dari Abjad Safa

King, G. (1990) "The Basalt Desert Rescue Survey and some preliminary remarks on the Safaitic inscriptions and rock drawings" Proceedings of the Seminar for Arabian Studies 20:55-78

Macdonald, M. C. A. (1992)  "Inscriptions, Safaitic" in The Anchor Bible Dictionary Vol 3 (editor in chief D N Freedman) Doubleday

Macdonald, M. C. A. (2000) "Reflections on the linguistic map of pre-Islamic Arabia" Arabian Archaeology and Epigraphy 11(1):28–79

Oxtoby, W. G. (1968) Some Inscriptions of the Safaitic Bedouin  American Oriental Society, Oriental Series 50.  New Haven, Connecticut

Winnett, F. V. and Harding, G. L. (1978) Inscriptions  from Fifty Safaitic Cairns  Toronto