Columbia subject headings:
Bolu (Turkey)--Description and travel.
Bolu (Turkey)--History.
Bolu (Türkiye)--Social life and customs.
Harvard subject headings:
Bolu (Turkey)--Description and travel.
Bolu (Turkey)--History.
Bolu (Türkiye)--Social life and customs.
Princeton subject headings:
Bolu (Turkey)--Description and travel.
Bolu (Turkey)--History.
Bolu (Türkiye)--Social life and customs.