Richard K. Payne (1999). The Shingon Ajikan: Diagrammatic Analysis of Ritual Syntax. , 29(3), 215–229.doi:10.1006/reli.1998.0179
Ronald S Green. "The Shingon Ajikan, Meditation on the Syllable ‘A’: An analysis of components and development." The Matheson Trust (2017) p. 1 - 33. doi:10.6084/m9.figshare.11859951
Koda, Yuun (1982). Hoju Nimon no Chuin-Ryu, Journal of esoteric Buddhism 139, pp.27-42. PDF
jstor.org
Quinter, D. (2018). Mantras and Materialities: Saidaiji Order Kōmyō Shingon Practices. Japanese Journal of Religious Studies, 45(2), 309–340. JSTOR26854487