Columbia subject headings:
Harvard subject headings:
Bolu (Turkey)--History.
Bolu İli (Turkey)--Economic conditions--20th century.
Bolu İli (Turkey)--History--20th century.
Bolu İli (Turkey)--Periodicals.
Bolu İli (Turkey)--Politics and government--20th century.
Bolu İli (Turkey)--Social conditions--20th century.
Yeşil yaprak.
Princeton subject headings:
Bolu (Turkey)--History.
Bolu İli (Turkey)--Economic conditions--20th century.
Bolu İli (Turkey)--History--20th century.
Bolu İli (Turkey)--Periodicals.
Bolu İli (Turkey)--Politics and government--20th century.
Bolu İli (Turkey)--Social conditions--20th century.
Periodicals.
Yeşil yaprak.