Prevalence of smoking cigarettes and beliefs regarding smoking habits among medical students: a cross-sectional study in Sudan oleh Ahmed Abdalla Jarelnape, Waled Ahmed, Suaad Omer, Aida Fadlala, Zeinab Ali, Mohamed Hassan, Ragaa Ahmed, Manal Hakami, Mujtaba Ali, Khalid Mohammed, Elwaleed Sagiron, Yahya Hussein Abdalla, Abdalla Osman, Eltayeb Abdelazeem, Hamza Balola