Introduction to the New Testament - Volume 1 - Theodor Zahn

Theodor Zahn (1838 - 1933) was a German Protestant theologian and a biblical scholar at the University of Erlangen. He was distinguished for his eminent scholarship, especially in connection with the New Testament canon. He stood at the head of the conservative scholarship at his time. 

Volume 1: The Epistle of James, the Epistles to the Galatians, the Epistles to the Thessalonians, the Epistles to the Corinthians, the Epistle to the Romans.