Glasgow Mathematical Journal, vol. 54, no. 2, page. 355 - 358, 2012-05
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY, vol. 131, no. 11, page. 3309 - 3317, 2003-01
PACIFIC JOURNAL OF MATHEMATICS, vol. 198, no. 2, page. 373 - 383, 2001-04
ABHANDLUNGEN AUS DEM MATHEMATISCHEN SEMINAR DER UNIVERSITAT HAMBURG, vol. 73, page. 289 - 295, 2003-01
AMERICAN JOURNAL OF MATHEMATICS, vol. 131, no. 2, page. 517 - 543, 2009-04
Ramanujan Journal, vol. 41, no. 1-3, page. 319 - 322, 2016-11