Coincidence site modules in 3-space
  The coincidence site lattice (CSL) problem and its generalization to   Z-modules in Euclidean 3-space is revisited, and various results and conjectures are proved in a unified way, by using maximal orders in quaternion algebras of class number 1 over real algebraic number fields. 
Michael Baake (Bielefeld), Peter Pleasants (Brisbane), Ulf Rehmann   (Bielefeld)