Gretchen Rubin (2015). “The Happiness Project (Revised Edition): Or, Why I Spent a Year Trying to Sing in the Morning, Clean My Closets, Fight Right, Read Aristotle, and Generally Have More Fun”, p.9, HarperCollins
Diana Gabaldon (2015). “The Outlander Series 8-Book Bundle: Outlander, Dragonfly in Amber, Voyager, Drums of Autumn, The Fiery Cross, A Breath of Snow and Ashes, An Echo in the Bone, Written in My Own Heart's Blood”, p.1186, Dell