Follow the link below to what, in my experience, is the most lengthy scholarly treatment of the relevant primary sources for the meaning of baptizein (“baptize”) availablable. The article just appeared online for free, though it was published in 2011:

Eckhard Schnabel, “The Meaning of Baptizein in Greek, Jewish, and Patristic Literature,” Filologia Neotestamentaria 24 (2011) 3-40.

No coherent discussion of this term (and baptism) can exclude the data of this article.