Русско-англо-русский юридический словарь

The term young professional generally refers to a young person not in school, usually in his/her late teens or early-mid 20's, who is employed in a profession or white-collar occupation. (Wikipedia)

And perhaps his most intriguing legacy are the unlikely corps of MPs, in their late teens and early 20s, who never dreamed of winning at the polls but are now full-fledged lawmakers by virtue of Layton's charisma. (Prince George Citizen)

We believe she was white, aged in her late teens to early 30s and of slender build. (BBC)

... adolescent idealism means that people in their late teens and early 20s hold to very high moral standards. (Human Adaptation to Extreme Stress: From the Holocaust to Vietnam)