A phone-based tobacco use cessation program for people living with HIV in Uganda and Zambia: study protocol for a randomized controlled trial oleh Heather Wipfli, Jim Arinaitwe, Fastone Goma, Lynn Atuyambe, David Guwatudde, Masauso Moses Phiri, Elizeus Rutebemberwa, Fred Wabwire-Mangen, Richard Zulu, Cosmas Zyambo, Kyra Guy, Ronald Kusolo, Musawa Mukupa, Ezekiel Musasizi, Joan S. Tucker