Figure 5: Geographical distribution of included papers
Source : authors
The stratification also shows a marked predominance of publications originating from developed countries. Regarding the classifications of countries based on their level of development created by the International Monetary Fund (IMF) (Nielsen, 2011), there are no publications from underdeveloped countries and only two papers come from developing countries (Brazil and India).

Stage 2.4: synthesizing data

\label{stage-2.4-synthesizing-data}
Stage 2.4 is responsible for the synthesis of data. Therefore, Table 2 presents all types of identified vehicles that are being used as alternatives to trucks in the last mile distribution, as well as the barriers, opportunities and benefits (economic, environmental and social) related to their use.
Table 2: Synthesis of the systematic literature review results.