Hi Patricia -
Congratulations on your new project! Nice face, well-lit, with lovely features.
Not much in the way of nuns, but here are a few links to people wearing severe black and white clothing:
http://www.abcgallery.com/V/velazquez/velazquez10.html
http://www.abcgallery.com/R/rembrandt/rembrandt6.html
http://www.abcgallery.com/R/repin/repin24.html