Table 2.

Mapping questions.

Question and ID		Mapping question	Rationale
MQ1a: References
	MQ1.1	How does the references co-citation network shape?	To understand the main topics and the development of research topics in PHD.b
	MQ1.2	How has the knowledge cluster evolved?	To identify which PHD topic has the most longevity and the newest hotspot.
	MQ1.3	What are the citation bursts of reference networks?	To explore the emerging PHD research topic characterized by articles.
MQ2: Keywords
	MQ2.1	What are the keyword bursts in recent years?	To explore the emerging research interests in PHD characterized by keywords.
MQ3: Disciplines
	MQ3.1	What does the discipline categories co-occurrence network shape?	To identify the trends of discipline categories that are involved in PHD.
	MQ3.2	What are the discipline categories bursts?	To explore the discipline categories that increased abruptly in PHD.

^aMQ: mapping question.

^bPHD: personal health data.