books.google.com - This work is an introduction to the basic tools of the theory of (partially) ordered sets such as visualization via diagrams, subsets, homomorphisms, important order-theoretical constructions, and classes of ordered sets. Using a thematic approach, the author presents open or recently solved problems...http://books.google.com/books/about/Ordered_sets.html?id=2esoXnolEWgC&utm_source=gb-gplus-shareOrdered sets
