Table 2.

Queries used for the search.

Indexer	Query
General query	(“Internet of Things” OR “IoT”) AND “Security” AND (“Authentication” OR “Authorization” OR “Identity” OR “Access control”) AND NOT (“Network” OR “Hardware” OR “RFID” OR “Protocol” OR “Cryptography” OR “Survey” OR “Study”)
IEEE Xplore	((“Abstract”: “Internet of Things” OR “Abstract”: “IoT”) AND (“Abstract”: “Authentication” OR “Abstract”: “Authorization” OR documentAbstract: “Identity” OR “Abstract”: “Access Control”) AND “Index Terms”: “Security” AND NOT(“Index Terms”: “Network” OR documentAbstract: “Hardware” OR “Abstract”: “Cryptography” OR “Abstract”: “Protocol” OR “Document Title”: “Survey” OR “Abstract”: “RFID” OR “Document Title”: "Study"))
ACM DL	Abstract: (IoT “Internet of Things”) AND Abstract: (“Authentication” OR “Authorization” OR “Identity” OR “Access Control”) AND Title: (-study -Survey) AND Abstract: (-Hardware -rfid -Cryptography) AND Keyword: (-Hardware -Physical -Network)
WoS SCIE	TI = (Internet of Things OR IoT) AND TS = (Authentication OR Authorization OR Identity OR Access Control) NOT TS = (Hardware OR Cryptography OR Protocol OR RFID OR Physical OR Network) NOT TS = (Survey OR Study) AND TS = Security
SpringerLink	‘(Authentication OR Authorization OR Identity OR “Access Control”) + title (“Internet of Things” OR IoT)’
ScienceDirect	(“Internet of Things” OR “IoT”) AND (“Authentication” OR “Authorization” OR “Identity” OR “Access control”) AND NOT (“Hardware” OR “Cryptography”)