M. H. Pestana et al.,  "Measaurement of the intelectual contribution of the issue: Synergetic effect of emotions on the travel motivation of senior tourists", in Proc. of the TMS Algarve 2016 – Tourism & Management Studies Int. Conf., Marisol Correia, José António Santos, Margarida Santos,Paulo Águas e Celísia Baptista, Ed., Olhão, UALgESGHT, 2016, vol. 1