I have restored the three See also references Are the two thesis references readily available to readers in the U S and U K Are there web links If not would it be feasible to put the thesis references online somewhere and then link to them Something that I am not clear about is whether a grey box model must always also be a statistical model The first paragraph from Statistical model General remarks is relevant here and is copied below A statistical model is a special type of mathematical model What distinguishes a statistical model from other mathematical models is that a statistical model is non deterministic Thus in a statistical model specified via mathematical equations some of the variables do not have specific values but instead have probability distributions i e some of the variables are stochastic In the equations of a grey box model is it required that there be stochastic variables I think that the article would benefit from making that clear