Columbia subject headings:
Hydrology.
Leonardo, da Vinci, 1452-1519--Knowledge and learning.
Leonardo, da Vinci, 1452-1519--Themes, motives.
Harvard subject headings:
Leonardo, da Vinci, 1452-1519--Criticism and interpretation.
Water in art
Princeton subject headings:
Leonardo, da Vinci, 1452-1519--Criticism and interpretation.