child marriage
http://id.loc.gov/authorities/subjects/sh85023372
https://en.wikipedia.org/wiki/Category:Child_marriage
https://en.wikipedia.org/wiki/Child_marriage
https://www.wikidata.org/wiki/Q1546421
A marriage or similar union, formal or informal, between an adult and a child or youth under a certain age, typically age eighteen.
HQ784.C55
marriages by age
child