https://www.amazon.com/s?k=the+verbal+behavior+approach+by+mary+barbera&crid=2E70V2Q259BR2&sprefix=verbal+behavior+mary%2Caps%2C242&ref=nb_sb_ss_ts-doa-p_1_20
Harris S. L, & Weiss M. J. (2007). Right from the start: Behavioral intervention for young children with autism (2nd ed.). Bethesda, MD: Woodbine House.