500 Days of Duolingo: What You Can (and Can't) Learn From a Language App - The New York Times
Learn Two Languages Together with Duolingo - ielanguages.com
Spanish- Is Duolingo in the wrong here? It's trying to force the 'usted' tense on me, but como te llamas is still correct, no? All the Spanish speakers I know tell me
Duolingo Review: Playful Lessons That Take You From Novice to Fluent - Learn Languages From Home