John Ruskin (1855). “Notes on Some of the Principal Pictures Exhibited in the Rooms of the Royal Academy, the Old and New Societies of Painters in Water Colours, the Society of British Artists and the French Exhibition”
John Ruskin (1869). “Modern Painters: pt. 6. Of leaf beauty. pt. 7. Of cloud beauty. pt. 8-9. Of ideas of relation: Of invention formal. Of invention spiritual”, p.276