Columbia subject headings:
Harvard subject headings:
Calendar, Japanese.
Japan--History--Chronology.
Princeton subject headings:
Calendar, Japanese--Handbooks, manuals, etc.
Emperors--Japan--Chronology--Handbooks, manuals, etc.
Japan--History--Chronology--Handbooks, manuals, etc.
Japan--Kings and rulers--Chronology--Handbooks, manuals, etc.