Effectiveness of an mHealth- and School-Based Health Education Program for Salt Reduction (EduSaltS) in China: Cluster Randomized Controlled Trial Within Scale-Up - Naibo Wang; Chen Wang; Puhong Zhang; Yinghua Li; Feng J He; Li Li; Yuan Li; Rong Luo; Dezhi Wan; Lewei Xu; Lifang Deng; Lei Wu (Journal of Medical Internet Research)