Search	Key Word (KW) or Subject Heading (SH)	Terms	Results
#1	KW	Play OR preten * OR game* OR toy OR recreation (all fields)	230,463
#2	SH	Recreation OR doll play OR toys OR childhood play behaviour OR games OR childhood play development OR playfulness	27,222
#3	KW	Train OR trains OR train set OR train track OR train play OR Thomas the tank engine OR Thomas and friends OR Hornby (all fields)	18,855
#5	SH	Railroad trains	659
#6		1 OR 2	230,744
#7		3 OR 5	18,855
#8		6 AND 7	1215
#9		Limit 8 to childhood (birth to 12 years) or adolescence (13 to 17 years)	254
Note. For key words related to ‘Train’, the term ‘train *’ was not used as it resulted in many irrel-evant articles, largely related to the term ‘training’. * reflects truncation of the search term.