Mapping populations at risk: improving spatial demographic data for infectious disease modeling and metric derivation. by Tatem, A, Adamo, S, Bharti, N, Burgert, C, Castro, M, Dorelien, A, Fink, G, Linard, C, John, M, Montana, L, Montgomery, MR, Nelson, A, Noor, A, Pindolia, D, Yetman, G, Balk, D