Columbia subject headings:
Acid rain--Washington (D.C.)
Building stones--Biodegradation--Washington (D.C.)
Harvard subject headings:
Acid rain--Washington (D.C.)
Building stones--Washington (D.C.)--Biodeterioration.
Princeton subject headings:
Acid rain--Environmental aspects--Washington (D.C.).
Building stones--Washington (D.C.)--Deterioration.