An ultra fuck-ton of human hand references.
Image (1) by GabrielCharest
Image (2) by Dhex
Images (3), (4) and (5) by kibbitzer
Image (6) and (7) by Erika Fabian
(Erika (to the best of my knoweldge) has no blog, but more of her work can be found [here] )
Image (8) by ConceptCookie
Image (9) by anatomy4sculptors.com
Image (10) by irysching (on DA and Tumblr)Please check out some of these sources, because there’s some more seriously good references from the same artists.