ROOTSWEB'S GUIDE TO TRACING FAMILY TREES <http://www.rootsweb.com/~rwguide/>. Do you know the difference between direct evidence and indirect evidence? What is a primary source and why does it matter? Lesson 12: Creating Worthwhile Genealogies -- Evidence, Sources, Citation, and Documentation. <http://www.rootsweb.com/~rwguide/lesson12.htm>.