Long-term results of short-course chemotherapy for pulmonary tuberculosis. (Final report). The third study: Comparative study of two regimens, 6RHZ and -6RHS (treatment was continued for 6 months after negative conversion of sputum by culture).:The Third Study: Comparative Study of Two Regimens, 6RHZ and-6RHS (treatment was continued for 6 months after negative conversion of sputum by culture)