Bond JC, Geller RJ, White KO, Hatch EE, Rothman KJ, Wise LA. Concordance of self-reported sexual intercourse frequency between members of mixed-sex couples attempting conception. Can J Hum Sex. 2022 Dec;31(3):342-53. doi: 10.3138/cjhs.2021-0059
Fleming AD, Xia X, McDicken WN, Sutherland GR, Fenn L. Myocardial velocity gradients detected by Doppler imaging. Br J Radiol. 1994 Jul 1;67(799):679-88. doi: 10.1259/0007-1285-67-799-679