1. School of Economics; University of Coimbra; Avenida Dias da Silva, 165 3004-512 Coimbra Portugal
2. School of Economics; Institute of Systems and Robotics; University of Coimbra; Avenida Dias da Silva, 165 3004-512 Coimbra Portugal
3. Department of Management and Economics; NECE-Research Center in Business Sciences; University of Beira Interior; Estrada do Sineiro 6200-209 Covilhã Portugal