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.14
John Ruskin (188?). “Works: "A joy forever." The art of England. "Our fathers have told us." The laws of Fesole. The pleasures of England. Fiction fair and foul. Notes on the construction of sheepfolds. Inaugural address ... Cambridge School of Art, October 29th, 1858. The storm cloud of the nineteenth century. The opening of the Crystal Palace”
John Ruskin (1872). “The Political Economy of Art: Being the Substance (with Additions) of Two Lectures Delivered at Manchester, July 10th and 13th, 1857”, p.56