Harvey, A. and Koopman, \.J. (1993). Forecasting hourly electricity demand using time–varying splines Journal of the American Statistical Association, 88(424):1228--1236.
Kleibergen, F. and \van Dijk\, \H.K.\ (1993). Non‐stationarity in garch models: A bayesian analysis Journal of Applied Econometrics, 8(1 S):S41--S61.
