Rufus M. Jones: Social Law in the Spiritual World. Headley, 1905.
Rufus M. Jones: Studies in Mystical Religion. Macmillan, 1909.
Rufus M. Jones: Children of the Light (Anthology of Quaker Mystics). Headley, 1909.
Evelyn Underhill: Mysticism. Macmillan, 1911.
William C. Braithwaite: The Beginnings of Quakerism. Macmillan, 1912.
William C. Braithwaite: Spiritual Guidance in Quaker Experience. Headley, 1909.
Edward Grubb: Authority and the Light Within. Clarke, 1908.
The Book of Discipline. Successive editions from 1783.
The Society of Friends. Encyclopædia Britannica. Eleventh edition.