Lord Philip Dormer Stanhope Chesterfield, Philip Dormer Stanhope Earl of Chesterfield (1855). “The Works of Lord Chesterfield: Including His Letters to His Son, Etc : to which is Prefixed, an Original Life of the Author”, p.153
Sogyal Rinpoche (2009). “The Tibetan Book of Living and Dying: The Spiritual Classic & International Bestseller: Revised and Updated Edition”, p.25, Harper Collins