William Shakespeare (2006). “The Poems: Venus and Adonis, The Rape of Lucrece, The Phoenix and the Turtle, The Passionate Pilgrim, A Lover's Complaint”, p.188, Cambridge University Press
Florence Nightingale, Lynn McDonald (2004). “Florence Nightingale on Public Health Care: Collected Works of Florence Nightingale”, p.31, Wilfrid Laurier Univ. Press
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.141