Evaluating an App-Based Intervention for Preventing Firearm Violence and Substance Use in Young Black Boys and Men: Usability Evaluation Study - Chuka Emezue; Dale Dan-Irabor; Andrew Froilan; Aaron Dunlap; Pablo Zamora; Sarah Negron; Janiya Simmons; Jayla Watkins; Wrenetha A Julion; Niranjan S Karnik (JMIR Formative Research, 2024)