Bourne JE, Sauchelli S, Perry R, Page A, Leary S, England C, Cooper AR. Health benefits of electrically-assisted cycling: a systematic review. Int J Behav Nutr Phy. 2018 Nov 21;15(1):116. doi: 10.1186/s12966-018-0751-8
Anderson IM, Jones S, Twiss J. Do negative cognitive style and personality predict depression symptoms and functional outcomes in severe bipolar and unipolar disorders? Int J Cogn Ther. 2009 Dec 15;2(4):343-53. doi: 10.1521/ijct.2009.2.4.343