A recent search in the Internet brought me to an interesting paper by Kadri Tammur of the Tartu University Library, in Estonia, discussing «Changes in Super Ex Libris in the course of time on the basis of tartu University Library collections» (http://www.leidykla.vu.lt/inetleid/knygot/42/straipsniai/str8.pdf).
Super libris as they are generally known were marks of ownership stamped on the bindings or the spine of a book usually representing the arms of the owner, wheter an individual or an institution, like a monastery a cathedral or a library.
Elena Hlodec - Painter - Graphic Artist - Ex Libris 