Columbia subject headings:
Architecture--Spain--History--20th century.
Architecture--Spain--History--21st century.
Roofs--Spain--Design and construction.
Harvard subject headings:
Architecture--Spain--History--20th century
Architecture--Spain--History--21st century.
Roofs--Spain--Design and construction.
Princeton subject headings:
Architecture--Spain--History--20th century.
Architecture--Spain--History--21st century.
Roofs--Spain--Design and construction.