Reversalkomplexität von Mehrbandautomaten unterhalb log. - Romain Gengler (1991)

Multicounter Automata with Sublogarithmic Reversal Bounds. - Romain Gengler (STACS, 1993)

The Alternation Hierarchy for Sublogarithmic Space is Infinite. - Burchard von Braunmühl; Romain Gengler; Robert Rettinger (Comput. Complex., 1993)

The Alternation Hierarchy for Machines with Sublogarithmic Space is Infinite. - Burchard von Braunmühl; Romain Gengler; Robert Rettinger (STACS, 1994)

Weakly Computable Real Numbers and Total Computable Real Functions. - Robert Rettinger; Xizhong Zheng; Romain Gengler; Burchard von Braunmühl (COCOON, 2001)

Monotonically Computable Real Numbers. - Robert Rettinger; Xizhong Zheng; Romain Gengler; Burchard von Braunmühl (Math. Log. Q., 2002)

Ershov's Hierarchy of Real Numbers. - Xizhong Zheng; Robert Rettinger; Romain Gengler (MFCS, 2003)

Closure Properties of Real Number Classes under CBV Functions. - Xizhong Zheng; Robert Rettinger; Romain Gengler (Theory Comput. Syst., 2005)