A systems analysis and improvement approach to optimizing syringe services programs’ delivery of HIV testing and referrals: Study protocol for a parallel-group randomized controlled trial (SAIA-SSP-HIV) - Angela R. Bazzi; Alexis M. Roth; Christopher F. Akiba; Shelby L. Huffaker; Sheila V. Patel; Jessica Smith; Rose Laurano; Stephen Orme; Gary A. Zarkin; Antonio Morgan-Lopez; Barrot H. Lambdin (PLoS ONE, 2025)