Lambek Grammars Are Context Free - Mati Pentus (LICS, 1993)

Language Completeness of the Lambek Calculus - Mati Pentus (LICS, 1994)

The conjoinability relation in Lambek calculus and linear logic. - Mati Pentus (J. Log. Lang. Inf., 1994)

Lambek Calculus and Formal Languages. - Mati Pentus (Logic Colloquium, 1995)

Models for the Lambek Calculus. - Mati Pentus (Ann. Pure Appl. Log., 1995)

IGPL/FoLLI Prize. - Mati Pentus (Log. J. IGPL, 1995)

Equivalence of Multiplicative Fragments of Cyclic Linear Logic and Noncommutative Linear Logic. - Mati Pentus (LFCS, 1997)

Product-Free Lambek Calculus and Context-Free Grammars. - Mati Pentus (J. Symb. Log., 1997)

Provability, complexity, grammars. - Lev D. Beklemishev; Mati Pentus; Nikolai K. Vereshchagin (American Mathematical Society, 1999)

Lambek calculus is NP-complete. - Mati Pentus (Theor. Comput. Sci., 2006)

Complexity of the Lambek Calculus and Its Fragments. - Mati Pentus (Advances in Modal Logic, 2010)

The Monotone Lambek Calculus Is NP-Complete. - Mati Pentus (Categories and Types in Logic, Language, and Physics, 2014)