Here's an excerpt from the TIME Magazine review from 5/30/77:
"A universe of plenty—as audiences can discover beginning this week in Star Wars, a grand and glorious film that may well be the smash hit of 1977, and certainly is the best movie of the year so far. Star Wars is a combination of Flash Gordon, The Wizard of Oz, the Errol Flynn swashbucklers of the '30s and '40s and almost every western ever screened....."
Whole review here.