Table 3.

Paper numbers in the search process.

Database	Initial Search	Inclusion/ Exclusion Criteria	Abstract	Full Text	Backward Snowballing
IEEE Explore	4438	81	42	30	32
Springer	6585	40	13	8	9
ACM Digital Library	8146	69	10	6	8
ScienceDirect	5529	52	3	2	3
Wiley	1072	16	1	1	1
SAE Mobilus	1726	17	8	5	5
Google Scholar	N/A	N/A	N/A	N/A	15
Total	27,496	275	77	52	73

N/A = Not applicable.