Bretnach, Liam, "The Cauldron of Poesy", Ériu #32, 1981, pp 45-93 -- scholarly translation and commentary
Carey, John, "The Waters of Vision and the Gods of Skill", Alexandria #1, 1991, pp 163-185 can be ordered from this link musings on filidecht and the Celtic symbolism of wisdom and inspiration. Both the Cauldron of Poesy and ogam are mentioned in this exquisitely written article, but the context is much deeper and concerns imbas or poetic inspiration, which is the underlying purpose of the cauldrons.
Henry, P.L., "The Cauldron of Poesy", Studia Celtica #14/15, 1979/1980, pp 114-128 -- scholarly translation and commentary
Laurie, Erynn Rowan, "The Cauldron of Poesy", Obsidian #2, Spring 1996, pp 23-30 -- this article is available online at this link
Laurie, Erynn Rowan, "The Cauldron of Poesy" 1998 translation, linked here.
Matthews, Caitlin & John, The Encyclopaedia of Celtic Wisdom, Element Inc, Rockport, 1994 -- while I disagree with some of their approach to the material and conclusions in chapter 7, Caitlin's translation is worth looking at. My primary disagreement is with her assumption that the Draoi and Filidh were all shamans.
note: The Cauldron of Poesy is a 7th century Irish text describing in poetic terms the training and knowledge of the fili.