Senchyna, Peter; et al. (2015-11), “Panchromatic Hubble Andromeda Treasury. XIV. The Period-Age Relationship of Cepheid Variables in M31 Star Clusters”, Astrophysical Journal813: 31, Bibcode: 2015ApJ...813...31S, doi:10.1088/0004-637X/813/1/31
Senchyna, Peter; et al. (2015-11), “Panchromatic Hubble Andromeda Treasury. XIV. The Period-Age Relationship of Cepheid Variables in M31 Star Clusters”, Astrophysical Journal813: 31, Bibcode: 2015ApJ...813...31S, doi:10.1088/0004-637X/813/1/31