Risky sexual practices among men who have sex with men in Northeast Brazil: results from four sequential surveys Práticas sexuais de risco de homens que fazem sexo com homens no No... oleh Rogério Costa Gondim, Ligia Regina Franco Sansigolo Kerr, Guilherme L. Werneck, Raimunda Hermelinda Maia Macena, Marta Kerr Pontes, Carl Kendall