[1] Washington CBS Local (2013) FBI: Hammers, Clubs Kill More People than Rifles, Shotguns CBS DC.
http://washington.cbslocal.com/2013/01/03/fbi-hammers-clubs-kill-more-people-than-rifles-shotguns/
[2] Scientific Working Group on Bloodstain Pattern Analysis (2009) FBI—Standards and Guidelines—Scientific Working Group on Bloodstain Pattern Analysis: Recommended Terminology.
http://www.fbi.gov/about-us/lab/forensic-science-communications/fsc/april2009/standards/2009_04_standards01.htm
[3] Toplikar, D. (2010) Blood Stain with Hammer Imprint Shown in Ex-FBI Agent’s Murder Trial—Las Vegas Sun News.
http://www.lasvegassun.com/news/2010/dec/13/blood-stain-showed-imprint-hammer-says-analyst-ex-/