69However, that principle must be reconciled with the concept of ‘undertaking’ and with the case-law according to which the fact that the parent company and its subsidiary constitute a single undertaking for the purposes of Article 81 EC empowers the Commission to address the decision imposing fines to the parent company of a group of companies. Thus, it must be held that the applicants were penalised personally for the infringement which they are deemed to have committed themselves on account of their economic, organisational and legal links with Dea Mineraloel resulting from the fact that they held all the latter’s capital (see, to that effect, Metsä-Serla and Others v Commission, paragraph 30 above, paragraph 34).