RT Journal Article SR Electronic T1 Recommendations on screening for breast cancer in average-risk women aged 40–74 years JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP 1991 OP 2001 DO 10.1503/cmaj.110334 VO 183 IS 17 A1 , YR 2011 UL http://www.cmaj.ca/content/183/17/1991.abstract