In its reference for preliminary ruling of March 4, 2011, the OLG Köln referred the follwoing question to the ECJ:Does Article 23(1) of the Regulation (EC) No 1008/2008 on common rules for the operation of air services in the Community, according to which optional price supplements are to be communicated in a clear, transparent and unambiguous way at the start of any booking process and are to be accepted by the customer on an opt-in basis, also apply to costs connected with air travel arising from services provided by third parties (in this case, an insurer offering travel cancellation insurance) and which are charged to the air traveller by the company organising the air travel together with the air fare as part of a total price?Case C-112/11 ebookers.com v. Bundesverband der Verbraucherzentralen und Verbraucherverbände