Evaluation of shelter programs for the urban poor: Principal findings Douglas H. Keare and Scott Parris World Bank Staff Working Paper No. 547, Washington D.C., 111 pp. Evaluation of sites and services projects: The experience from lusaka, zambia Michael Bamberger, Bisghwapura Sanyal and Nelson Valverde World Bank Staff Working Paper No. 548, Washington D.C., 203 pp. Evaluation of sites and services projects: The evidence from el salvador Michael Bamberger, Edgardo Gonzalez-Polio and Umnuay Sae-Han World Bank Staff Working Paper No. 549, Washington D.C., 286 pp