Hello to all 

I would like to know what are the stages of development of adolescence according to the recognized international references. The lancet classifies them in 2: 10-14 years and 15-19 years. However, I often see a classification according to 3 stages of development 11-14 years, 15-17 years or 18-20 years. Can we use this classification in 3 stages? 

Thank you