## 3 Research Methodology
### Material Collection
This is especially true for papers addressing VRPs that could be applied to both humanitarian operations and commercial purposes. In this case, unless the humanitarian setting is mentioned in detail, such a paper is dismissed and focus is only paid on those that specifically addressed classified humanitarian operations through the application of VRP in the event of disasters. From Figure 1, it could be briefly said that the interest in publishing papers addressing the application of VRPs in classified humanitarian operations is gradually increasing from the year 2012 and reaching its peak in the year 2018. The same trend could also be seen in each of the sources of publication type namely the journal and conference proceedings. (Figure 2). When considering all of the sources of publications individually, it could also be observed that each publication contributing roughly to the same amount of papers, ranging \begin{table}
\begin{tabular}{l c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Source of Publication**} & \multicolumn{10}{c}{**Year**} \\ \cline{2-11}  & **2010** & **2011** & **2012** & **2013** & **2014** & **2015** & **2016** & **2017** & **2018** & **2019** & **2020** & **Total** \\ \hline Transp. Res. Part E: Log. \& Transp. Review & - & - & 1 & - & 1 & - & - & - & 1 & - & - & 3 \\ Int. Transactions in OR & - & - & - & - & 1 & - & 1 & - & - & - & 1 & 3 \\ Euro. J. of OR & - & - & - & - & - & - & 1 & 1 & - & 1 & 4 \\ J. of Industrial. and Sys. Eng & - & - & - & - & - & - & 1 & - & - & 1 & - & 2 \\ Annals of OR & - & - & - & - & - & - & 1 & - & - & 2 & - & 3 \\ Int. J. of Disaster Risk Reduction & - & - & - & - & - & - & - & 1 & 1 & - & 1 & 3 \\ Sustainability & - & - & - & - & - & - & - & 1 & - & 1 & - & 2 \\ ISPRS Int. J. of Geo-Information & - & - & - & - & - & - & - & 1 & 1 & - & - & 2 \\ J. of HL and SCM & - & - & - & - & - & - & - & - & 3 & - & - & 3 \\ Socio-Econ. Planning Science & - & - & - & - & - & - & - & - & 1 & 1 & - & 2 \\ Comp. \& Industrial Eng. & - & - & - & - & - & - & - & - & 2 & 2 & 4 \\ OR & - & - & - & - & - & - & - & - & - & - & 2 & 2 \\ Maths. & - & - & - & - & - & - & - & - & - & - & 2 & 2 \\ Comp. \& OR & - & - & 1 & - & 1 & - & - & - & - & - & 2 \\ Transp. Res. Part B: Methodology & - & - & 1 & - & - & - & 1 & - & - & - & - & 2 \\ Transp. Res. Part D: Transp and Env. & - & - & - & - & - & - & - & - & - & 2 & - & 2 \\ Conf: CICTP 2019 & - & - & - & - & - & - & - & - & - & 4 & - & 4 \\ Conf: Trans, Res. Procedia & - & - & - & - & - & - & - & - & 1 & - & 3 & 4 \\ PhD Thesis & - & - & - & - & - & - & - & - & 2 & - & - & 2 \\ Tech Report & - & - & - & - & - & - & - & 1 & - & - & - & 1 \\ Others (J. \& Conf: 1 Paper) & 0 & 0 & 0 & 2 & 3 & 5 & 6 & 5 & 28 & 15 & 7 & 71 \\ \hline TOTAL & 0 & 0 & 2 & 3 & 5 & 6 & 12 & 9 & 39 & 28 & 19 & 123 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Distribution of Papers Based on Different Publications Over the Years. Figure 3: Distribution of Papers Based on Different Publication. from the value of 1 to 4. Thus, no clear source of publication is seen dominating the scope of this review by a large margin. Finally, it could be said that the papers that are published in journals contribute to roughly twice the amount of conference papers, suggesting a healthy amount of comprehensive work published when compared to preliminary studies.