Adolf Harnack - Wikipedia: Article on the theologian, historian and essayist who was one of the major contributors to the theories of the social gospel movement.
Adolf von Harnack: A biography of Adolf von Harnack from the Dictionary of Modern Western Theology.
Harnack, Adolf: Outlines of the History of Dogma: Evangelical criticism of Harnack's views regarding the Gospel of John and the Trinity.
Marcion: An excerpt from Adolf von Harnack's, "History of Dogma."