A Course in Universal Algebra

For those hesitant to click: the site contains an out-of-print original Springer-Verlag Graduate Text in Mathematics 1981 edition of "A Course in Universal Algebra" by Stanley N. Burris and H.P. Sankappanavar in PDF. Universal algebra is the use of set theory to study "algebraic structures" - <a href="http://en.wikipedia.org/wiki/Universal_algebra" rel="nofollow">http://en.wikipedia.org/wiki/Universal_algebra</a>

I see...we need Universal Algebra because Abstract Algebra isn't abstract enough.