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
Epictetus, Marcus Aurelius, Lucius Annaeus Seneca (2016). “Stoic Six Pack: Meditations of Marcus Aurelius, Golden Sayings, Fragments and Discourses of Epictetus, Letters from a Stoic and The Enchiridion”, p.76, Enhanced Media Publishing