Volumes of integral congruence hyperbolic manifolds. John G. Ratcliffe; Steven T. Tschantz — 1997 Journal für die reine und angewandte Mathematik
The volume spectrum of hyperbolic 4-manifolds. Ratcliffe, John G.; Tschantz, Steven T. — 2000 Experimental Mathematics
Complements of tori and Klein bottles in the 4-sphere that have hyperbolic structure. Ivanšić, Dubravko; Ratcliffe, John G.; Tschantz, Steven T. — 2005 Algebraic & Geometric Topology