Reihe Trends in LogicG. Schurz × The Is-Ought ProblemAn Investigation in Philosophical LogicG. SchurzSpringer NetherlandeBook2013 The Is-Ought ProblemAn Investigation in Philosophical LogicG. SchurzSpringer NetherlandSoftcover2010 The Is-Ought ProblemAn Investigation in Philosophical LogicG. SchurzSpringer NetherlandHardcover1997