PT - JOURNAL ARTICLE AU - Wilhelm Kreyes TI - Butting heads over bicycle helmets DP - 2002 Aug 20 TA - Canadian Medical Association Journal PG - 337--337 VI - 167 IP - 4 4099 - http://www.cmaj.ca/content/167/4/337.1.short 4100 - http://www.cmaj.ca/content/167/4/337.1.full SO - CMAJ2002 Aug 20; 167