Standardized milk yield of the herd on day of test: herd standard cow production / J. Dommerholt, S.R. Sijbrandij, W.M.G. WismansExtrapolation of lactation in progress and correction for age and season of calving : the individual standard cow production and the lactation value / J. Dommerholt, S.R. Sijbrandij, W.M.G. Wismans