Freire, Paulo; Ridolfi, Alessandro; Kramer, Michael. Long-term observations of the pulsars in 47 Tucanae - II. Proper motions, accelerations and jerks. Monthly Notices of the Royal Astronomical Society. 2017, 471 (7640): 857–876. Bibcode:2017MNRAS.471..857F. arXiv:1706.04908. doi:10.1093/mnras/stx1533.
Freire, Paulo; Ridolfi, Alessandro; Kramer, Michael. Long-term observations of the pulsars in 47 Tucanae - II. Proper motions, accelerations and jerks. Monthly Notices of the Royal Astronomical Society. 2017, 471 (7640): 857–876. Bibcode:2017MNRAS.471..857F. arXiv:1706.04908. doi:10.1093/mnras/stx1533.
Shapley, Harlow; Sawyer, Helen B. A Classification of Globular Clusters. Harvard College Observatory Bulletin. August 1927, 849 (849): 11–14. Bibcode:1927BHarO.849...11S.
Freire, Paulo; Ridolfi, Alessandro; Kramer, Michael. Long-term observations of the pulsars in 47 Tucanae - II. Proper motions, accelerations and jerks. Monthly Notices of the Royal Astronomical Society. 2017, 471 (7640): 857–876. Bibcode:2017MNRAS.471..857F. arXiv:1706.04908. doi:10.1093/mnras/stx1533.