An Elementary Characterization of the Category of (Free) Relational Systems. Eric Mendelsohn — 1970 Mathematische Zeitschrift
An Elementary Characterization of the Category of Partly Ordered Sets. Eric Mendelsohn — 1971 Mathematische Zeitschrift
An elementary characterization of the category of relational systems Eric Mendelsohn — 1969 Commentationes Mathematicae Universitatis Carolinae
Colouring planar mixed hypergraphs. Kündgen, André; Mendelsohn, Eric; Voloshin, Vitaly — 2000 The Electronic Journal of Combinatorics [electronic only]