Yang H, Lin Y, Long Y, Ma Q, Zhou C. Predicting Cardioembolic Stroke with the B-Type Natriuretic Peptide Test: A Systematic Review and Meta-analysis. Journal of Stroke and Cerebrovascular Diseases. 2014 Aug;23(7):1882–9. doi: 10.1016/j.jstrokecerebrovasdis.2014.02.014.