Siegfried Echterhoff and Dana P. Williams, Crossed products by -actions, J. Funct. Anal. 158 (1998), 113-151.

Astrid an Huef, Iain Raeburn, and Dana P. Williams, An equivariant Brauer semigroup and the symmetric imprimitivity theorem, Trans. Amer. Math. Soc., 352(10):4759-4787, 2000.

Siegfried Echterhoff and Dana P. Williams, Locally inner actions on -algebras, J. Operator Theory 45 (2001), 131-160.

Iain Raeburn, Aidan Sims, and Dana P. Williams, Twisted actions and obstructions in group cohomology, In -algebras (Münster, 1999), pages 161-181. Springer, Berlin, 2000.

Dana P. Williams, A primer for the Brauer group of a groupoid, In Groupoids in analysis, geometry, and physics (Boulder, CO, 1999), volume 282 of Contemp. Math., pages 21-34. Amer. Math. Soc., Providence, RI, 2001.

Astrid an Huef and Dana P. Williams, Ideals in transformation-group -algebras, J. Operator Theory, 48(3, suppl.):535-548, 2002.

Astrid an Huef, Iain Raeburn, and Dana P. Williams, Proper actions on imprimitivity bimodules and decompositions of Morita equivalences, J. Funct. Anal. 200 (2003), 401-428.

Siegfried Echterhoff and Dana P. Williams, Central twisted transformation groups and group -algebras of central group extensions, Indiana Univ. Math. J. 51 (2002), 1277-1304.