Columbia subject headings:
Architects--Finland.
Architectural firms--Finland.
Architecture--Finland--History--20th century.
Architecture--Finland--History--21st century.
Helin, Pekka.
Harvard subject headings:
Architects--Finland.
Architectural firm--Finland.
Architecture--Finland--21st century.
Architecture--Finland--History--20th century
Helin & Co Architects--Catalogs.
Helin, Pekka.
Princeton subject headings:
Architects--Finland.
Architectural firm--Finland.
Architecture--Finland--21st century.
Architecture--Finland--History--20th century.
Helin, Pekka.