Columbia subject headings:
Aragon (Spain)--History.
Science--Spain--Aragon--History.
Technology--Spain--Aragon--History.
Harvard subject headings:
Aragon (Spain)--History.
Science--Spain--Aragon--History.
Technology--Spain--Aragon--History.
Princeton subject headings:
Castile (Spain)--History.
Science--Spain--Castile--History.
Technology--Spain--Castile--History.