2011

• The Structure of Endomorphism Monoids of Strong Semilattices of Left Simple Semigroups (Dissertation)
• Algebraic Structure of Endomorphism Monoids of Finite Graphs (Dissertation)

2007

• Crossing number results on completely regular embeddings
• Archimedian graphs
• Injectivities of S-acts and S-poacts (Dissertation)
• On transitive Cayley graphs of strong semilattices of completely simple semigroups (Dissertation)

2005

• Rees Matrix Semigroups with Transitive Cayley Graphs
• Almost all graphs are rigid
• The Structure of graph homomorphisms

2004

• Characterisation Of Clifford Semigroup Digraphs

2003

• Endo properties of graphs
• Games on Graphs (State Examination Thesis)
• Groupoids and Cayley graphs

2002

• On completely regular graphs on surfaces of higher genus

2001

• Spectra and endomorphism monoids of special graphs
• Application of Schur Rings in Algebraic Combinations (Dissertation)
• On total colouring of graphs

2000

• Homological Classification of Monoids by Projectivities of Right Acts (Dissertation)
• A Max-Plus Algebra and Timetable Modelling and Simulation of Bus and Train Timetables

1999

• Properties of Fuzzy Acts

1998

• Automorphism groups of cospectral graphs
• Monoids of graphs with at most 8 vertices and 16 endomorphisms
• Functors on graphs

1997

• Use of theorem provers using the example of graph theory
• Representations of Petri nets and semigroups (Habilschrift)

1996

• Graphs of injective and projective S-acts
• Edge morphisms of graphs and hypergraphs (state examination thesis)

1994

• The structure of the Endomorphism Monoid of a graph (Dissertation)
• Continuity of ordered sets
• Monoid-preserving graph construction

1993

• Endomorphisms of coproducts of finite graphs
• Unretractivity of box and cross products
• Category of hypergraphs (state examination thesis)

1992

• Algebraic properties of the isotone wreath product of ordered semigroups

1991

• Relations between simple, regular and truncatable semigroups

1990

• Homorphisms and congruences of graphs
• On the endomorphism monoid of the lexicographic product of finite graphs (dissertation)
• Regularity properties of endomorphism monoids of bipartite graphs (state examination thesis)

1989

• Act regularity and actinversity of special semigroups
• Eigenvalues and paths in graphs
• Wreath products of monoids, groups and graphs
• Unretractivities of graphs without loops
• Condorcet, Simpson and Weber solutions on graphs; their existence and correspondence (dissertation)
• Plurality solutions on graphs and injective metric spaces (dissertation)

1987

• Endomorphism monoids of graphs and distributive laws for compositions of graphs
• Categorical constructions and endomorphism monoids of graphs

1986

• Strong endomorphisms and compositions of graphs
• Algebraic properties of the zero wreath product of monoids
• Algebraic properties of the zero wreath product of monoids and acts
• Isometric subgraphs of Hamming graphs (Dissertation)

1985

• Optimal locations and voting paradoxes on graphs (group work)

1984

• Block diagonalisability of adjacency matrices (state examination thesis)
• Eigenvalues in semirings (group work)
• Semigroups of graphs (group work)
• Vector space graphs and generalisations

1983

• The matching polynomial and operations of graphs
• Relations between the automorphism group and the spectrum of a graph
• Graphs whose adjacency matrices are not derogatory (group work)
• Mathematical models for the description of real problems using the example of an automatic packaging system (state examination thesis)
• Planarity for hypergraphs

1982

• Mathematical modelling of a work path problem (state examination thesis)
• Generalisations of colourings and chromatic polynomials of graphs and hypergraphs
• Intersection graphs of finite Abelian groups (state examination thesis)
• Mathematical modelling of traffic light circuits (group work)

1981

• Graph operations and spectra
• Regular semigroups of residuated mappings (group thesis)

1980

• On the representation of matroids
• Finite fields, representations and applications (state examination thesis)
• Linear factorisation of algebraic terms (state examination thesis, secondary school)
• Elementary equations and polynomial rings (state examination thesis)
• Intersection graphs
• Theoretical and application-oriented problems in connection with Euler paths

1979

• The problem of parallels (group work, state examination paper for secondary school)
• Eigenvalues of graphs - The importance of eigenvalues for the stability behaviour of directed graphs under the influence of pulse processes (group work, state examination thesis)
• Polynomials and graphs (group work, state examination thesis)

1978

• Groups in Graph Theory (State Examination Thesis)

1975

• Cycles and co-cycles in hypergraphs (Bielefeld)
• Dynamic programming and shortest paths in graphs (State examination thesis, Bielefeld)
• Graph-theoretical methods for the determination of cliques in sociometric data (State examination thesis, Bielefeld)

1974

• Introduction to graph theory as a tool for solving mathematisation problems (State examination thesis, Bielefeld)