## 2 Research Methodology
### Searched Libraries  
For searching the literature of the domain, popular libraries were selected, such as IEEE Xplore, Science Direct, ACM, Springer, Hindawi, and Taylor and Francis. The following are the libraries used and the associated web links for reference:  
* Science Direct library: [[https://www.sciencedirect.com/](https://www.sciencedirect.com/)]([https://www.sciencedirect.com/](https://www.sciencedirect.com/)) accessed date: 29 December 2019
* ACM library: [[https://dl.acm.org/](https://dl.acm.org/)]([https://dl.acm.org/](https://dl.acm.org/)) accessed date: 30 December 2019
* Springer library: [[https://link.springer.com/](https://link.springer.com/)]([https://link.springer.com/](https://link.springer.com/)) accessed date: 30 December 2019
* Taylor and Francis library: [[https://www.tandfonline.com/](https://www.tandfonline.com/)]([https://www.tandfonline.com/](https://www.tandfonline.com/)) accessed date: 31 December 2019
* Hindawi library: [[https://www.hindawi.com](https://www.hindawi.com)]([https://www.hindawi.com](https://www.hindawi.com)) accessed date: 31 December 2019
* IEEE Xplore library: [[https://ieeexplore.ieee.org/Xplore/home.jsp](https://ieeexplore.ieee.org/Xplore/home.jsp)]([https://ieeexplore.ieee.org/Xplore/home.jsp](https://ieeexplore.ieee.org/Xplore/home.jsp)) accessed date: 29 December 2019  
Each of the libraries was searched for the formulated query and search results were filtered to include papers ranging from 2015 to early 2020. Some pilot searches were also performed to get the most relevant search results. Among the two alternative formats depicted in Table 3, most of the libraries confined the search to more specific queries with quotations as compared to an alternative one. The search result of each library in response to the provided query is shown in Table 4. \begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**S. No** & **Libraries** & **Keywords Query** & **Total** & **Included** & **Period** \\ \hline \multirow{4}{*}{1} & \multirow{4}{*}{ACM} & (\"intelligent decision” OR “IDSS” OR “IDSSs” OR “decision & & & \\  & & support system” OR “DSS”) AND (”machine learning” OR “algorithm”) AND (“multicriteria” OR “multi-criteria” OR “multiple criteria” OR “multiple criteria” OR “MCDM”) & 45 & 17 & 2015–2020 \\ \hline \multirow{4}{*}{2} & \multirow{4}{*}{IEEE Xplore} & (intelligent decision OR IDSS OR IDSSs OR intelligent decision support system OR DSS) AND (machine learning OR algorithm) AND (multicriteria OR multi-criteria OR multiple criteria OR MCDM) & 62 & 20 & 2015–2020 \\ \hline \multirow{4}{*}{3} & \multirow{4}{*}{Science Direct} & (\"intelligent decision” OR “IDSS” OR “IDSSs” OR “intellig decision support system” OR “DSS” AND (“machine learning” OR “algorithm”) AND (“multicriteria” OR “multi-criteria” OR “multiple criteria” OR “MCDM”) & 458 & 42 & 2015–2020 \\ \hline \multirow{4}{*}{4} & \multirow{4}{*}{Springer} & (\"intelligent decision” OR “IDSS” OR “IDSSs” OR “intellig decision support system” OR “DSSs”) AND (“machine learning” OR “algorithm”) AND (“multicriteria” OR “multiple criteria” OR “MCDM”) & 555 & 77 & 2015–2020 \\ \hline \multirow{4}{*}{5} & \multirow{4}{*}{[PERSON] and [PERSON]} & (“intelligent decision” OR “IDSSs” OR “IDSSs” OR “intellig decision support system” OR “DSSs”) AND (“machine learning” OR “multi-criteria” OR “multiple criteria” OR “MCDM”) & 89 & 17 & 2015–2020 \\ \cline{1-1} \cline{3-3}  & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary statistics of query execution (2015–2020).