The Sorgenfrey topology is a join of orderable topologies Paul R. Meyer — 1973 Czechoslovak Mathematical Journal
Cardinal invariants of bitopological spaces Ralph D. Kopperman; Paul R. Meyer — 1989 Časopis pro pěstování matematiky
On tightness in chain-net spaces Ignacio Jané; Paul R. Meyer; Petr Simon; Richard Gordon Wilson — 1981 Commentationes Mathematicae Universitatis Carolinae
Boundaries in digital planes. Khalimsky, Efim; Kopperman, Ralph; Meyer, Paul R. — 1990 Journal of Applied Mathematics and Stochastic Analysis