1)Horace Walpole (1782) : The History of Modern Taste in Gardening, Ursus Press, p.42, rpt. Strawberry Hill Press, 1995.
2)Antoine Joseph Dezallier DArgenville: La Theorie et la Pratique du Jardinage, Paris, 1709, 1713, 1722, 1732, 1743, 1760; 1703: anonymously, 1760 edition, rpt. G.Olms Verlag, 1972. Trans. By John James: The Theory and Practice of Gardening, 1712.
3)Peter Willis (2002) : Charles Bridgeman and the English Landscape Garden, pp.18-21, Elysium Press Publishers.
4)Peter Willis (1973) : From Desert to Eden: Charles Bridgemans Capital Stroke, Burlington Magazine, cxv, pp.150-57.
5)Miles Hadfield (1963) : History of the Ha-Ha, Country Life, May 30, pp.1261-62.