Estudio (3) Teenagers (2) Sexual intercourse (2) Sex (2) Human behavior (2) Evaluation (2) Universe (2) Evaluación (2) Sexualidad (2) Universo (2) Conducta (2) Adolescentes (2) Relaciones sexuales (2) Conocimiento (2) Triangulation (1) Teachers (1) Subways (1) Students (1) Research (1) Quality of products (1) Letters (1) Generals (1) Families (1) Education (1) Drinking of alcoholic beverages (1) Diagnosis (1) Design (1) Communication (1) Capital (1) Nicotine addiction (1)