Successful application of PSF-R techniques to the case of the globular cluster NGC 6121 (M 4)D. Massari, A. Marasco, O. Beltramo-Martin, J. Milli, G. Fiorentino, E. Tolstoy and F. KerberA&A, 634 (2020) L5DOI: https://doi.org/10.1051/0004-6361/201937359
