books.google.com - Categories for the Working Mathematician provides an array of general ideas useful in a wide variety of fields. Starting from the foundations, this book illuminates the concepts of category, functor, natural transformation, and duality. The book then turns to adjoint functors, which provide a description...http://books.google.com/books/about/Categories_for_the_Working_Mathematician.html?id=MXboNPdTv7QC&utm_source=gb-gplus-shareCategories for the Working Mathematician
