Thomas Cogswell Upham (1844). “Principles of the Interior Or Hidden Life: Designed Particularly for the Consideration of Those who are Seeking Assurance of Faith and Perfect Love”, p.283
John William Gibson, William Henry Crogman, Booker T. Washington, Fannie Barrier Williams (1902). “Progress of a race: or, The remarkable advancement of the American Negro from the bondage of slavery, ignorance and poverty to the freedom of citizenship, intelligence, affluence, honor and trust”
Robert Fortune (1847). “Three Years' Wanderings in the Northern Provinces of China: Including a Visit to the Tea, Silk, and Cotton Countries; with an Account of the Agriculture and Horticulture of the Chinese, New Plants, Etc”, p.85