2013, Kevin Feige, quoted in Laura Ciarolla, "Marvel announces third 'Avengers' film", The Daily Athenaueum (West Virginia University), Volume 125, Issue 86, 30 January 2013, page 3:It Ant-Man will, of course, be firmly planted in the MCU but a different corner than we've seen before.
2015, Dan Casey, 100 Things Avengers Fans Should Know & Do Before They Die, Triumph Books (2015), ISBN 9781629370866, page 128:... Hydra is a sprawling global organization with highly advanced technology that has opposed S.H.I.E.L.D, the Avengers, and nearly every major superhero group in the MCU.
2015, Colin Harvey, Fantastic Transmedia: Narrative, Play and Memory Across Science Fiction and Fantasy Storyworlds, Palgrave Macmillan (2015), ISBN 9781137306043, page pages 84-85:It is interesting to note that, while Coulson is used to suture the various MCU films together and latterly to tie the Agents of SHIELD television show into the MCU, this has not occurred at other points in the franchise.