1. Cima RR, Kollengode A, Garnatz J, et al. Incidence and characteristics of potential and actual retained foreign object events in surgical patients. J Am Coll Surg 2008; 207:80-87

2. https://en.wikipedia.org/wiki/Never events

3.WHO Guidelines for Safe Surgery 2009 http://apps.who.int/iris/bitstream/10665/44185/1/9789241598552_eng.pdf

4.https://www.businesswire.com/news/home/20120215005917/en/RF-Surgical%E2  %80%99s-Radio-Frequency-Detection-System-Leading

5. Retained Surgical Sponges: Findings from Incident Reports and a Cost-Benefit Analysis of Radio frequency Technology J Am Coll Surg ,2014:354-364c