Left linear theories - A generalization of module theory. - Bodo Pareigis; Helmut Röhrl (Appl. Categorical Struct., 1994)

Convexity theories 0. Foundations. - Helmut Röhrl (Appl. Categorical Struct., 1994)

Complements and the Krull-Schmidt Theorem in arbitrary categories. - Bodo Pareigis; Helmut Röhrl (Appl. Categorical Struct., 1995)

Convexity theories IV. Klein-Hilbert parts in convex modules. - D. Pumplün; Helmut Röhrl (Appl. Categorical Struct., 1995)

Convexity Theories V: Extensions of Absolutely and Totally Convex Modules. - D. Pumplün; Helmut Röhrl (Appl. Categorical Struct., 2000)

Completeness and Cocompleteness of RSmod1 N. - Helmut Röhrl (Appl. Categorical Struct., 2000)

Convexity Theories VII. Discrete Gamma-Convex Modules. - Helmut Röhrl (Appl. Categorical Struct., 2001)

On N-Summations, I. - Jay Fillmore; D. Pumplün; Helmut Röhrl (Appl. Categorical Struct., 2002)

On N-Summations, II. - Helmut Röhrl (Appl. Categorical Struct., 2005)

gamma-Frames, GGamma-Algebras and Measurable Spaces. - Helmut Röhrl (Appl. Categorical Struct., 2010)