And it's not just Streeter's Four Gospels (see previous post) but several other full on-line books made available on Katapi including:
Introduction to the New Testament by A H McNeile.
First published Oxford University Press 1927.
A Historical Introduction to the New Testament by Robert M Grant.
First published by Collin's 1963.
The Riddle of the New Testament by Sir Edwyn Hoskyns & Noel Davey.
First published Faber & Faber 1931.