Roberto Cignoli The Algebras of Lukasiewicz Many-Valued Logic: A Historical Overview. 69-83 2006 conf/birthday/2006mundici Algebraic and Proof-theoretic Aspects of Non-classical Logics http://dx.doi.org/10.1007/978-3-540-75939-3_5 db/conf/birthday/mundici2006.html#Cignoli06