Philip Bishop, bibliographer and rare book specialist, published a number of shorter essays on special bindings of the Rubáiyát that were published by Thomas B. Mosher. One of the bindings is by Hans Asper, the other by George Bayntun. The essays are available on Bishop’s Mosher Press website: http://thomasbirdmosher.net/index1.html.
The direct links to the essays are
http://thomasbirdmosher.net/files/hans-asper-binding.pdf, for the Asper binding, and
http://thomasbirdmosher.net/files/acquisitions-since-endpapers.pdf for the Bayntun binding essay.
Phil Bishop also published a large bibliographic volume on the Mosher Press editions, which includes of course the many rubáiyáts of Omar Khayyám.