Columbia subject headings:
Animals--Poetry.
Birds--Poetry.
English poetry--Middle English, 1100-1500--History and criticism.
Harvard subject headings:
Animals--Poetry.
Birds--Poetry.
English poetry--Middle English, 1100-1500--History and criticism
Princeton subject headings:
Animals in literature.
Birds in literature.
English poetry--Middle English, 1100-1500--History and criticism.
Fables, English--History and criticism.