books about the problems of unknown proportions
If you do not find what you're looking for, you can use more accurate words.
# unknown parentage
# Adolescents of unknown parentage
# unknown angel
# The rights of the child of unknown parentage
# About children of unknown parentage
# Does not inherit from unknown parentage
# About girls of unknown parentage
# Aggressive behavior of unknown parentage
# Guarantee of unknown parentage between jurisprudence and law
# Sponsorship of unknown parentage in the arts
# Protection of the unknown
# unknown names
# Unknown built-in translation problems
# Orphans and people of unknown parentage
# Anonymous rights
# Social Anxiety of Unidentified Persons
# Anonymous rulings
# rank unknowns
# proportions population
# Diminishing proportions
