They have brackets on the back that you can use to hang them, plus we used some super strong glue to attach them to the walls and bottom of shelf as well. (beneathmyheart.net)
The Bancroft Library, University of California, Berkeley 2009 Ink on paper, wooden shelf Dimensions variable 16 sheets, each: 11 5/8 x 8 1/4 inches (29.6 x 21 cm) Overall as installed approx: 136 3/4 x 8 1/2 x 8 inches Height from floor measured from bottom of shelf: 11 5/8 inches (29.7 cm) ARG # VD2009 - 002 (andrearosengallery.com)
Secure molding to bottom of shelf with brads, then nail in return pieces. (hgtv.com)