Stable planes. - Markus J. Stroppel (Discret. Math., 1994)

Polarities and unitals in the Coulter-Matthews planes. - Norbert Knarr; Markus J. Stroppel (Des. Codes Cryptogr., 2010)

Non-Existence of isomorphisms between certain unitals. - Theo Grundhöfer; Boris Krinn; Markus J. Stroppel (Des. Codes Cryptogr., 2011)

Desargues, doily, dualities and exceptional isomorphisms. - Bernhild Stroppel; Markus J. Stroppel (Australas. J Comb., 2013)

A non-classical unital of order four with many translations. - Theo Grundhöfer; Markus J. Stroppel; Hendrik Van Maldeghem (Discret. Math., 2016)

On elation Laguerre planes with a two-transitive orbit on the set of generators. - Günter F. Steinke; Markus J. Stroppel (Finite Fields Their Appl., 2018)

Embeddings of unitals such that each block is a subline. - Theo Grundhöfer; Markus J. Stroppel; Hendrik Van Maldeghem (Australas. J Comb., 2021)

Linear spaces embedded into projective spaces via Baer sublines. - Theo Grundhöfer; Markus J. Stroppel; Hendrik Van Maldeghem (Comb. Theory, 2022)