I don't know where one would find references to the sixteen insight
knowledges in the Sutta Pitaka, but one can find them in the
Patisambhidamagga.
The seven stages of purification form the central theme of the Rathavinita =
Sutta, Majjhimanikaya, Sutta 24, "The Discourse on the Relay of Chariots."
One can find the word aniccaanupassanañaana in the Patisambhidamagga for
example. Rest assured that the Vipassana method as taught in Burma is not
just something developed later from the commentaries, but is the authentic =