Bauer, Walter. Orthodoxy and Heresy in Early Christianity.

Bultmann, Rudolf, Jesus and the Word

Harnack, Adolf von, The Mission and Expansion of Christianity in the First Three Centuries (here)

Harnack, History of Dogma, vol. 1 (here).

Harnack, Lehrbuch der Dogmengeschichte, vol. 1 (here)

Harnack in English (here)

Strauss, David Friedrich. Das Leben Jesu, kritisch bearbeitet (1935/1936)

Strauss, David Friedrich, Multiple Works

Weiss, Johannes, Die Predigt Jesu von Reich Gottes, 1892 (cf. here)

Wrede, Paul [here]

Wrede, Paulus [here]

Lots of Links

Princeton Theological Commons Search