Stephen V. Ward (2003), 'Re-examining the International Diffusion of Planning', in Robert Freestone (ed.), Urban Planning in a Changing World: The Twentieth Century Experience, London: E and FN Spon, pp. 40-60.

An intriguing footnote in the life of lldefons Cerda, author of the 1'859 plan for Barcelona's Eixample (Extension), is that Georges-Eugene Haussmann, simultaneously engaged on the remodelling of Paris, is reported to have offered to buy Cerda's plans and studies (Estape, 1996, p. 55). Cerda apparently refused, saying that he had drawn them up for Catalonia. If true, and the evidence rests on family recollection rather than a documentary source, this episode suggests that there was some degree of international linkage at a very early stage in the development of modem planning. In turn, Cerda's refusal to sell may also partially explain why his remarkable innovatory work including, in 1867, the Teoria General de la Urbanizaci6n (General Theory of Urbanization), effectively the fIrst modem theoretical work on urban planning, had a negligible international impact.