TABLE 2.
Distribution of reviewed sources.
| Type of source | Frequency | Percentage | Cumulative percentage |
| Journal articles | 107 | 86.29 | 86.29 |
| Books | 7 | 5.65 | 91.94 |
| Book chapters | 10 | 8.06 | 100 |
| Total | 124 | 100 |
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