G. Bergman: An invitation to general algebra and universal constructions.
Springer 2015, 570p. Eur 39.

809 Angela Bozzini: Concetti di algebra generale e di programmazione.
Tesi, Ferrara 1989.

12696 Stanley Burris/H. Sankappanavar: A course in universal algebra.
Springer 1981.

P. Cohn: Universal algebra. Harper & Row 1965.

16599 Paul De Witte: A single axiom for closure operations.
Algebra Univ. 12 (1981), 268-269.

G. Graetzer: Universal algebra. Springer 1979.

3256 David Hobby/Ralph McKenzie: The structure of finite algebras. AMS 1988.

1181 Thomas Ihringer: Allgemeine Algebra. Teubner 1988.

24761 Hans Lausch/Wilfried Nöbauer: Algebra of polynomials. North-Holland 1973.

R. Laver: The left distributive law and the freeness of an algebra of 
elementary embeddings. Circa 1991.

8331 J. Rutten: A calculus of transition systems (towards universal
coalgebra). CWI Report CS-R9503 (1995), 25p.

8332 J. Rutten: Elements of generalized ultrametric domain theory.
CWI Report CS-R9507 (1995), 31p.

G. Schmidt/T. Stroehlein: Relations and graphs.
Springer 1993, 300p. DM 88. A purely mathematical concept and its application 
to computer science. Seems to be interesting and well-written.