Carvalho, M. (2016). Mean, what do you mean? The American Statistician 70(3): 270–274.

Keyfitz, N. and Littman, G. (1979). Mortality in a heterogeneous population. Population Studies 33(2): 333–342.

Patil, G.P. (2014). Weighted distributions. (Wiley StatsRef: Statistics Reference Online).

Preston, S.H. (1976). Family sizes of children and family sizes of women. Demography 13(1): 105–114.

Schoen, R. (2013). Modeling multigroup populations. Boston: Springer Science and Business Media.

Sen, P.K. (1987). What do the arithmetic, geometric and harmonic means tell us in length-biased sampling? Statistics and Probability Letters 5(2): 95–98.

Sheps, M.C. (1964). On the time required for conception. Population Studies 18(1): 85–97.

Sheps, M.C., Menken, J., and Radick, A.P. (1973). Mathematical models of conception and birth. Chicago: University of Chicago Press.

Vaupel, J.W., Manton, K.G., and Stallard, E. (1979). The impact of heterogeneity in individual frailty on the dynamics of mortality. Demography 16(3): 439–454.

Vaupel, J.W. and Missov, T.I. (2014). Unobserved population heterogeneity: A review of formal relationships. Demographic Research 31(2): 659–686.