TY - JOUR T1 - Pertussis vaccine: why do some parents say no? JF - Canadian Medical Association Journal JO - CMAJ SP - 498c LP - 498 VL - 140 IS - 5 AU - P. J. Feher Y1 - 1989/03/01 UR - http://www.cmaj.ca/content/140/5/498c.abstract ER -