Relationship Between Product Features and the Prices of e-Cigarette Devices Sold in Web-Based Vape Shops: Comparison Study Using a Linear Regression Model. - He, Yanyun; Yang, Qian; Alish, Yousef; Ma, Shaoying; Qiu, Zefeng; Chen, Jian; Wagener, Theodore; Shang, Ce (JMIR Formative Research, 2024)