@inproceedingsRösler_1995, place=Providence, Rhode Island, series=Contemporary Mathematics, title=Convolution algebras which are not necessarily positivity-preserving, volume=183, DOI=10.1090/conm/183/02068, booktitle=Applications of Hypergroups and Related Measure Algebras, publisher=American Mathematical Society, author=Rösler, Margit, year=1995, pages=299–318, collection=Contemporary Mathematics