Uncertainty in Weighting Formulary Apportionment Factors and Its Impact on After-Tax Income of Multinational Groups
R. Ortmann, Uncertainty in Weighting Formulary Apportionment Factors and Its Impact on After-Tax Income of Multinational Groups, 2015.

Uncertainty in Weighting Formulary Apportionment Factors
R. Ortmann, Die Betriebswirtschaft 75 (2015) 161–177.

Can the CCCTB Alleviate Tax Discrimination against Loss-Making European Multinational Groups?
R. Ortmann, C. Sureth-Sloane, Can the CCCTB Alleviate Tax Discrimination against Loss-Making European Multinational Groups?, 2014.