"Multiplicity Type and Subalgebra Structure in Universal Algebras", Matthew Gould, [w:] „Pacific Journal of Mathematics”, Nr 3, t. 26, R. 1968; "Multiplicity Type and Subalgebra Structure in Infinitary Universal Algebra", Matthew Gould, [w:] „Colloqium Mathematicum”, t. 24, R. 1971 : [recenzja]

Bulletin of the Section of Logic, Tom 1, Numer 3 (1972) s. 72-76
Jan Zygmunt , Matthew Gould (aut. dzieła rec.)