“…RS that consider groups of users (Jameson & Smyth, 2007;Boratto & Carta, 2011) are starting to expand and to be used in different areas: tourism (Ardissono, Goy, Petrone, Segnan, & Torasso, 2003;McCarthy, Salamó, Coyle, McGinty, Smyth, & Nixon, 2006), music (Chao, Balthrop, & Forrest, 2005), TV (Yu, Zhou, Hao, & Gu, 2006) and web (Pazzani & Billsus, 2007).…”