Appendix Table 1.

Search Engines Assessed in Included Studies

	Ask	Bing	Google	Yahoo	YouTube	Other
Study authors
Akinleye et al.,12 2018			X
Akpolat and Kurdal,13 2020					X
Bruce-Brand et al.,14 2013	X	X	X	X
Cassidy et al.,15 2018					X
Celik et al.,16 2020					X
Dalton et al.,17 2015	X	X	X	X		AOL
DeFroda et al.,18 2019		X	X
DeFroda et al.,19 2018		X	X	X
Devitt et al.,20 2017		X	X	X		AOL, Lycos
Duncan et al.,21 2013	X	X	X	X
Dy et al.,5 2012		X	X	X
Garcia et al.,22 2014		X	X	X
Goldenberg et al.,23 2019		X	X	X
Gosselin et al.,24 2013		X	X	X
Houck et al.,25 2019		X	X	X
Nwachukwu et al.,26 2018		X	X	X
O'Neill et al.,27 2014		X	X	X
Somerson et al.,28 2018		X	X	X
Starman et al.,31 2010			X	X
Wang et al.,29 2017		X	X	X
Zhang et al.,30 2016		X	X	X
Total	3	16	18	16	3	3
%	14	76	86	76	14	14