Table 1. The literature search process.

Database	Search string
ACM digital library	(“mobile app*” OR smartphone OR phone) AND (review* OR comment*) AND (requirement* OR feature*) AND (extract* OR mine OR analy*)
IEEE Xplore	(“mobile app*” OR smartphone OR phone) AND (review* OR comment*) AND (requirement* OR feature*) AND (extract* OR mine OR analy*)
ScienceDirect	TITLE-ABSTR-KEY (“mobile app*” OR smartphone OR phone) AND TITLE-ABSTR-KEY (review* OR comment*) AND TITLE-ABSTR-KEY (requirement* OR feature*) AND TITLE-ABSTR-KEY (extract* OR mine OR analy*)
Scopus	TITLE-ABS-KEY (“mobile app*” OR smartphone OR phone) AND TITLE-ABS-KEY (review* OR comment*) AND TITLE-ABS-KEY (requirement* OR feature*) AND TITLE-ABS-KEY (extract* OR mine OR analy*)
SpringerLink	(“mobile app*” OR smartphone OR phone) AND (review* OR comment*) AND (requirement* OR feature*) AND (extract* OR mine OR analy*)