Smoking Cessation Smartphone App for Nondaily Smoking With Telephone Onboarding: Proof-of-Concept Randomized Controlled Trial - Bettina B Hoeppner; Kaitlyn R Siegel; Allison E Futter; Diadora Finley-Abboud; Alivia C Williamson; Christopher W Kahler; Elyse R Park; Susanne S Hoeppner (JMIR mHealth and uHealth)