In collaboration with Paulo Tirao:
 
Compact flat manifolds with holonomy group Z2 + Z2
Proceedings of the American Mathematical Society, 124 no. 8, (1996), 2491--2499.

Compact flat manifolds with holonomy group Z2+Z2 (II)   pdf article
Rendiconti del Seminario Matem\'atico dell'Universit\'a di Padova, 101 (1999), 99--136.

Five-Dimensional Bieberbach Groups with Holonomy Group Z2 + Z2
Geometriae Dedicata, 77 no.2, (1999) 149--172.


In collaboration with Roberto Miatello:

Isospectral Hantzsche-Wendt Manifolds
Journal  für die Reine und Angewandte Mathematik (Crelle's Journal), 515 (1999), 1--23.

Hantzsche-Wendt Manifolds of Dimension 7       (article in ps or dvi)
Proceedings of the VII International Conference ``Differential Geometry and its Applications", Brno,
Cech Republic 1998, (1999) 379--390.

 Flat Manifolds Isospectral on p-forms                arXiv: math.DG/0303276
Journal of Geometric Analysis, 11 (2001), 649--667.

Comparison of Twisted p-form Spectra for Flat Manifolds with Diagonal Holonomy
Annals of Global Analysis and Geometry. 21 no. 4, (2002), 341--376.

Length spectra and p-spectra of compact flat manifolds   arXiv: math.DG/0110325   
Journal of Geometric Analysis, 13 (2003), 631--657.


In collaboration with Carolyn S. Gordon:

Boundary volume and length spectra of Riemannian manifolds: What the middle degree Hodge spectrum doesn't reveal
 Annales de l'Insitut Fourier, 83 no.7, (2003), 2297--2314 .  arXiv: math.DG/0111016         


In collaboration with Andrzej Szczepański:

Generalized Hantzsche-Wendt Flat Manifolds, 16 pages.      arXiv: math.GT/0208205
to appear in Revista Matemática Iberoamericana, 21 no.3, (2005)


In collaboration with Peter G. Doyle.

Tetra and Didi the cosmic spectral twins 
Geometry and Topology 8 (2004), 1227-1242


Preprints (submitted):

Describing the platycosmsarxiv: math.DG/0311476
in collaboration with John H. Conway.

Hearing the platcosms,     arxiv: math.DG/0311470 
in collaboration with John H. Conway.

(Z_2^k)-manifolds are isospectral on forms     arXiv: math.DG/0408285
in collaboration with  Roberto Miatello and Ricardo Podestá.


In preparation:

Spectrum and length spectrum of closed hyperbolic surfaces via the Selberg trace formula
in collaboration with Peter G. Doyle.

Shifted lattices with the same theta series

Mutually p-isospectral flat Riemannian manifolds

Representation theory and isospectrality of certain locally homogeneous manifolds
in collaboration with Roberto Miatello.