WATTLES, Jeffrey. Living in truth, beauty, and goodness : values and virtues. Eugene, Oregon : Cascade Books, [2016]. ©2016. 1 online zdroj (220 stran). Dostupné na internetu: <http://search.ebscohost.com/login.aspx?direct=true&db=nlebk&AN=1339959&lang=cs&site=eds-live&ebv=EK&ppid=Page-__-1> ISBN 978-1-4982-3972-1.