Sampén Celis, J. D., L. F. Varela Pinedo, C. Díaz Vélez, T. Tello Rodríguez, and P. J. Ortiz Saavedra. “Validation of Kogan’s Attitudes towards Old People Scale and an Assessment of Primary Care Level Personnel Attitudes towards the Elderly”. ACTA MEDICA PERUANA, Vol. 29, no. 3, Sept. 2012, pp. 148-54, http://54.39.98.165/index.php/AMP/article/view/1205.