Central Europe is a subregion whose membership varies by classification. The Wikipedia article consulted for this entity gives the region's often-included member states but no single total area figure.
What would resolve this A reference that states an exact set of member states matching this atlas's own list (Austria, Croatia, Czech Republic, Germany, Hungary, Liechtenstein, Lithuania, Poland, Slovakia, Slovenia, Switzerland) and gives a summed area for that exact set.
OpenCentral Europe (Wikipedia)