RT Journal Article SR Electronic T1 Painful periods in adolescents JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP E560 OP E560 DO 10.1503/cmaj.201972 VO 193 IS 16 A1 Olga Kciuk A1 Sari Kives YR 2021 UL http://www.cmaj.ca/content/193/16/E560.abstract