“…On the other, many papers have shown interest in focusing on a certain specific research topic, highlighting transport and connectivity (seven papers, 5%), migration (nine papers, 6.3%) cultural variables mainly related to religion, common language, or cultural values (18 papers, 12.6%) and trade and visa policies (10 papers, 7%). More recently, and motivated by the international context, some published papers have focused on security threats (10 papers, 7%), mainly in terms of terrorist attacks (Fourie et al., 2020; Khalid, Okafor, & Aziz, 2020; Okafor & Khalid, 2021) and security spending (Khalid, Okafor, & Aziz, 2020; Okafor, Tan, & Khalid, 2021). With this categorization by research topic, we aim to provide a useful guide to reference most influential papers that use gravity models in the tourism economic literature.…”