Columbia subject headings:
Harvard subject headings:
Adventure stories.
Balkan Peninsula--Description and travel--Juvenile fiction.
Balkan Peninsula--Description and travel.
Christian life--Juvenile fiction.
Cossacks--Juvenile fiction.
Islam--Juvenile fiction.
Soviet Union--Description and travel--Juvenile fiction.
Soviet Union--Description and travel.
Tutors and tutoring--Juvenile fiction.
Voyages and travels--Juvenile fiction
Princeton subject headings:
Balkan Peninsula--Description and travel.
Soviet Union--Description and travel.