From Paper Maps to the Web: A DIY Digital Maps Primer by Mauricio Giraldo Arteaga | The New York Public Library
▻http://www.nypl.org/blog/2015/01/05/web-maps-primer
▻http://mapwarper.net
Map Warper is a web tool that lets you upload your scanned maps and provides a simple interface for you to geo-reference them (or “rectify” in geo parlance).