Photometric Monitoring and Period Changes in SX Phoenicis Star XX Cygni. IV. Withers, S. ; Kantorowitz-Sapers, A. ; Parsons, J. ; Wu, J. Y. ; Delaney, P. A. Abstract Publication: Journal of the Royal Astronomical Society of Canada Pub Date: December 2021 Bibcode: 2021JRASC.115..238W