Two basic references:
http://en.wikipedia.org/wiki/Locus_of_control
http://www.wilderdom.com/psychology/loc/LocusOfControlWhatIs.html
and one very charming by Terri Gregory, artist, mother, wife, and student of art therapy
http://www.bing.com/images/search?q=locus+of+control&view=detail&id=4EE3A44B9388D53859A905CDC60999CB34AB6500&first=1&FORM=IDFRIR