Thomson Reuters have released the annual round of updates to their ranked list of journals by journal impact factor JIF in yesterday’s Journal Citation Reports. Impact Factors have come under increasing scrutiny in recent years for their lack of transparency and for misleading attempts at research assessment. Last year the San Francisco Declaration on Research Assessment DORA took a groundbreaking stance by explicitly disavowing the use of impact factors in assessment. This document has since drawn support worldwide and across the academic community. But what exactly are Journal Impact Factors and why are they cause for so much concern? Here is a reading list that highlights some helpful pieces we’ve been able to feature on the Impact blog over the last few years.