Table 3. Digital library search strategy.

Digital library	Search query	Applied filter
(WoS Core Collection) SCI-Expended SCIE ESCI A&HCI	TITLE: (mobile learning) OR TITLE: (m-learning) OR TITLE: (m-learning) OR TITLE: (mobile assisted language learning) OR TITLE: (MALL) OR TITLE: (mobile language learning) OR TITLE: (Language Learning) OR TITLE: (English Language Learning) OR TITLE: (L2) OR TITLE: (ESL) OR TITLE: (EFL) AND TITLE: (Comprehension) OR TITLE: (Reading Comprehension) AND TITLE: (grammar) AND TITLE: (Pedagogy) AND TITLE: (Idioms) AND TITLE: (Vocabulary) AND TITLE: (Educational Institute) OR TITLE: (Institute) OR TITLE: (University) OR TITLE: (College) OR TITLE: (School) OR TITLE: (Elementary School) OR TITLE: (Primary School) Defining	2010–2020