Behavioural support and nicotine replacement therapy for smokeless tobacco cessation: protocol for a pilot randomised-controlled multi-country trial oleh Faraz Siddiqui, Linda Bauld, Ray Croucher, Cath Jackson, Ian Kellar, Mona Kanaan, Subhash Pokhrel, Rumana Huque, Romaina Iqbal, Javaid Ahmed Khan, Ravi Mehrotra, Kamran Siddiqi, on behalf of the ASTRA Global Health Research Group