TY - JOUR T1 - Polarity JF - Canadian Family Physician JO - Can Fam Physician SP - e90 LP - e90 DO - 10.46747/cfp.6703e90 VL - 67 IS - 3 AU - Yelena Zavalishina Y1 - 2021/03/01 UR - http://www.cfp.ca/content/67/3/e90.abstract N2 - ER -