Ballester, R., and M.-I. Porras. “The Historical Meaning of Serological Surveys As a Laboratory Technology Applied to the Inmunization Campaigns. The Case of Poliomyelitis in Spain”. Asclepio, vol. 61, no. 1, June 2009, pp. 55-80, doi:10.3989/asclepio.2009.v61.i1.272.