Policy options to improve leadership of middle managers in the Australian residential aged care setting: a narrative synthesis

Table 2 Number of references by source and tier

Sources	Tier 1	Tier 2	Tier 3
Electronic database	3044	766	499
Hand search	285	129	122
Relevant references	79	79	74
Grey literature	1076	73	72
Total	4484	1047	767

ISSN: 1472-6963