II.13.9 Copyright notice for pre-existing rights  When the contractor retains  pre-existing rights  on parts of the  results , reference must be inserted to  that effect when the  result  is used as set out in Article I.10.1, with the  following disclaimer: ‘© —  year  — European Union. All rights reserved. Certain parts are licensed under conditions to the EU’ , or with  any other equivalent disclaimer as the contracting authority may consider best appropriate, or as the  parties may agree on a case-by-case basis. This does not apply where inserting such reference would  be impossible, notably for practical reasons.  II.13.10 Visibility of Union funding and disclaimer  When making use of the  results , the contractor must declare that they have been produced under a  contract with the Contracting Authority and that the opinions expressed are those of the contractor  only and do not represent the contracting authority’s official position. The contracting authority may  waive this obligation in writing or provide the text of the disclaimer. II.14 FORCE MAJEURE  II.14.1 If a party is affected by  force majeure , it must immediately  notify the other party,  stating the nature of the circumstances, their likely duration and foreseeable effects.  II.14.2 A party is not liable for any delay or failure to perform its obligations under the contract  if that delay or failure is a  result of  force majeure . If the contractor is unable to fulfil its  contractual obligations owing to  force majeure , it has the right to remuneration only for the  services actually provided.  II.14.3 The parties must take all necessary measures to limit any damage due to  force majeure. II.15 LIQUIDATED DAMAGES  II.15.1 Delay in delivery  If the contractor fails to perform its contractual obligations within the applicable time limits set in this  contract, the contracting authority may claim liquidated damages for each day of delay using the  following formula: 0.3 x ( V/d) where  V is the price of the relevant purchase or deliverable or  result  or, failing that, the amount  specified in Article I.4.1;  d  is the duration specified for delivery of the relevant purchase or deliverable or  result  or, failing  that, the duration of  performance of the contract  specified in Article I.3.3 expressed in days.  Liquidated damages may be imposed together with a reduction in price under the conditions laid down  in Article II.16.  II.15.2 Procedure  The contracting authority must  formally notify the contractor of its intention to apply liquidated  damages and the corresponding calculated amount. The contractor has 30 days following the date of receipt to submit observations. Failing that, the  decision becomes enforceable the day after the time limit for submitting observations has elapsed. If the contractor submits observations, the contracting authority, taking into account the relevant  observations, must  notify  the contractor: (a) of the withdrawal of its intention to apply liquidated damages; or 26 