These are in order from left to right; a Titian, a Bourguereau and (I think) a Rubens. The Titian was drawn first and is quite tight, in the other 2 I tried to loosen things up a bit. These thumbnails are great for experimenting with what materials work best together- the second drawing uses Conte for the darkest darks and the third uses compressed charcoal.
I enjoy doing these, they're quick to do and remind me what I should be looking out for on larger drawings. So if I get up in the morning and don't know where to start I will do a few of these. Considering a baby is due this week (should have been last week) I need things like this to keep me going when everything goes crazy.