[1] Univ Catol Portuguesa, Res Ctr Management & Econ, Porto, Portugal
[2] Univ Urbino Carlo Bo, Dept Commun Sci Humanities & Int Studies, Urbino, Italy
[3] Univ Catolica Portuguesa, Catolica Porto Business Sch, Porto, Portugal
[4] Univ Goettingen, Dept Mkt & Ebusiness, Retail Logist & Innovat Lab, Gottingen, Germany
[5] Univ Goettingen, Dept Mkt & Ebusiness, Pl Goettinger Sieben 3, D-37073 Gottingen, Germany