Given the input sentence, please extract the subject and object containing a certain relation in the sentence according to the following relation types, in the format of "relation1: word1, word2; relation2: word3, word4". Relations include: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

Telefónica customer base totalled 329.4 million accesses after incorporating GVT in Brazil and Digital Plus in Spain, both key assets to reinforce Telefónica’s growth potential and leadership in quality services.

Answer: owned_by: GVT, Telefónica; owner_of: Telefónica, GVT