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| Description | Results (frequency) |
| a. Overview of existing literature | |
| Total published studies (1977–2019) | 125 |
| Sources (Journals, reports, books, etc.) | 83 |
| Authors' keywords | 178 |
| Total authors | 375 |
| Authors of multi-author documents | 356 |
| Authors per document | 3 |
| Co-authors per document | 3.43 |
| Collaboration index | 3.46 |
| Mean citations per document | 8.15 |
| b. Types of documents | |
| Original articles | 62 |
| Review articles | 14 |
| Letters/correspondence | 15 |
| Editorials | 11 |
| Others | 23 |
