John Ruskin (1854). “On the nature of Gothic architecture: and herein of the true functions of the workman in art. Being the greater part of the 6th chapter of the 2nd vol. of 'Stones of Venice'. [48 p.].”, p.18
John Ruskin (1875). “Proserpina: Studies of Wayside Flowers, While the Air was Yet Pure Among the Alps, and in the Scotland and England which My Father Knew”, p.95
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
John Ruskin, Louisa Caroline Tuthill (1872). “The True and the Beautiful in Nature, Art, Morals, and Religion, Selected from the Works of John Ruskin”, p.242
John Ruskin “The stones of Venice (cont'd) Seven lamps of architecture. Lectures on architecture and painting, delivered at Edinburgh in Nov. 1853. An inquiry into some of the conditions at present affecting the study of architecture in our schools”