Columbia subject headings:
Harvard subject headings:
Ecology--Russia (Federation)--Leningradskai︠a︡ oblastʹ--Periodicals.
Ecology--Russia (Federation)--Leningradskai︠a︡ oblastʹ--Statistics--Periodicals.
Leningradskai︠a︡ oblastʹ (Russia)--Environmental conditions--Periodicals.
Leningradskai︠a︡ oblastʹ (Russia)--Environmental conditions--Statistics--Periodicals.
Princeton subject headings:
Environmental--Russia (Federation)--Leningradskai︠a︡ oblastʹ--Periodicals.
Envrionmental protection--Russia (Federation)--Saint Petersburg--Periodicals.
Leningradskai︠a︡ oblastʹ (Russia)--Environmental conditions--Periodicals.
Saint Petersburg (Russia)--Environmental conditions--Periodicals.