The Biblical Roots of Quaker Worship explores biblical passages that led early Friends to waiting worship and spirit-led prophetic vocal ministry (based on the 10th proposition “Concerning Worship” of Barclay’s Apology).
An Historical Note on Recording Gifts in the Ministry by Brian Drayton of New England YM
A Description of the Qualifications Necessary to a Gospel Minister. This wonderful 18th century volume by Samuel Bownas offers invaluable advice to those who feel led to vocal ministry during worship. [Note: The above link allows you to read the original for free. It is also available in hardcover for $15 from Pendle Hill Publications here]
An Epistle to Friends Coming Forth in Ministry by Charles Marshall, excerpted from the Life of Charles Marshall.