## 2 Methods
### Search Strategy  
A search of peer-reviewed published literature was implemented in February 2020 for articles related to the use of MAR technologies in ASD interventions. The search process was conducted using keywords that link to our topic, and the keywords combined by the Boolean operators are determined as follows: (\"Autism\"' OR \"Autism Spectrum Disorder\" OR \"ASD\") AND (\"Mobile augmented reality\" OR \"AR\" OR \"Augmented reality\") AND (\"Mobile\" OR \"Tablet\" OR \"Smartphone\" OR \"Phone\" OR \"Smartglass\").  
The following inclusion criteria were used:  
* Articles published after 2010;
* Studies published in English;
* Research from peer-reviewed journals or conferences, books and lecture notes;
* Articles focused on mobile AR applications for ASD people;
* Articles must be a full or short version (not an abstract).  
Seven online databases linked to the scientific fields relevant to both technologies and ASD interventions were selected to search primary studies for this review. These databases include Web of Science, Scopus, ACM Digital Library, ScienceDirect, IEEE Xplore, SpringerLink, PubMed and Google Scholar. The search and selection process is described in Figure 1, with the following steps:  
1. A separate search was carried out in the identified online databases, and search results were manually imported to EndNote for further screening;  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**No.** & **Research Questions** & **Data Extraction Process** \\ \hline RQ1 & What channels are used to publish research articles in ASD interventions exploiting AR technology? & Venue and year of publication is required. \\ \hline RQ2 & What device was used? & The used technological devices are required. \\ \hline RQ3 & What are the targeted population? & Characteristics of participants should be defined. \\ \hline RQ4 & For what purposes have been applied the proposed solution? & The targeted skills of selected studies should be extracted. \\ \hline RQ5 & What research designs are used in the studies? & The research design of selected studies should be defined. \\ \hline RQ6 & What methods are used to evaluate the performance of participants with the provided AR technology intervention? & The assessment methodology should be presented. \\ \hline RQ7 & What are the outcomes obtained by the application of the proposed solutions? & The major outcomes of the study should be presented. \\ \hline RQ8 & Which settings are used in the primary studies? & Details on the setting (classroom, home, controlled research environment, etc.) are required. \\ \hline RQ9 & How sustainable the outcome of the intervention is? & Detailed information about maintenance. \\ \hline RQ10 & How generalized the intervention result is? & Detailed information about generalization. \\ \hline \hline \end{tabular}
\end{table}
Table 1: Research questions.  
2. Individually check and remove the incorrect references (such as abstracts or contents, etc.) from the EndNote;
3. To remove all the duplicates studies;
4. To check the research title, abstract, introduction and conclusion, and exclude documents that do not meet the inclusion criteria;
5. Add the research we missed from other review paper;
6. Perform a full-text review to delete non-mobile AR studies (such as device used computer or Kinect, etc.).