| Management internaţional I Popa, R Filip Editura Economică, 1999 | 89 | 1999 |
| Tranzacţii de comerţ exterior: negociere, contractare, derulare I Popa, C Țăranu, D Călin Editura Economică, 2002 | 54 | 2002 |
| Tehnica operaţiunilor de comerţ exterior I Popa Editura Economică, 2008 | 40 | 2008 |
| Tranzacţii comerciale internaţionale I Popa International Trade Transactions], Economic Publishing House, Bucharest, 1997 | 32 | 1997 |
| Negocierea comercială internaţională I Popa Editura Economică, 2006 | 30 | 2006 |
| Global logistics, competitiveness and the new incoterms P Ioan, BM Gabriela, PD Mihai Annals of the University of Oradea 159, 2013 | 24 | 2013 |
| International management I Popa, F Radu Economica, Bucharest, 1999 | 19 | 1999 |
| Best practices in customs procedures I Popa, MG Belu, DM Paraschiv, AM Marinoiu Amfiteatru Economic Journal 17 (40), 1095-1107, 2015 | 17 | 2015 |
| Bursa I Popa Adevărul, 1994 | 15 | 1994 |
| Models and practice of retail location on the romanian market G Cazabat, MG Belu, I Popa, DM Paraschiv Amfiteatru Economic 19 (45), 493, 2017 | 14 | 2017 |
| Bursa, vol. I şi II I Popa Editura Adevărul, Bucureşti, 1995 | 13 | 1995 |
| Management strategic, ed I Popa Economică, Bucureşti, 2004 | 10 | 2004 |
| Procese de prelucrare cu fascicule şi jeturi NI Marinescu, D Nanu, E Lăcătuş, I Popa, R Marinescu, R Savastru Bucureşti: Institutul Naţional de Optoelectronică, 152-245, 2000 | 10 | 2000 |
| Management internaţional, Ed I Popa, R Filip Economică, Bucureşti, 1999 | 10 | 1999 |
| Afaceri internaţionale: tehnica operaţiunilor de export-import I Popa, MG Belu Editura ASE, 2018 | 8 | 2018 |
| Growth poles and national competitivness P Ioan, BM Gabriela Annals of the University of Oradea, Economic Science Series 18 (1), 33-39, 2009 | 8 | 2009 |
| Technical operations of foreign trade I Popa Economic Publishing House. Bucharest 2, 17-59, 2008 | 8 | 2008 |
| Management international R Filip, I POPA Editura Economica, BucureÅŸti, 1999 | 8 | 1999 |
| General management I Popa București, Organizational culture, Publishing House of the Academy of …, 2005 | 7 | 2005 |
| External trade transactions I Popa Economic Publishing House, Bucharest, 2002 | 7 | 2002 |
