@InCollection{Fit07,
    Author       = "Fitting, M.",
    Year         = "2007",
    Title        = "{Modal Proof Theory}",
    Editor       = "Blackburn, P. and van Benthem, J. and Wolther, F.",
    BookTitle    = "{Handbook of Modal Logic}",
    Pages        = "86-135",
    Publisher    = "Elsevier",
    Comment      = "TPTPRef"
}