You won't be learning a language from a single source ever. Duolingo is the most efficient for what it does, including teaching grammar, actually. Yes, it migh

You won't be learning a language from a single source ever. Duolingo is the most efficient for what it does, including teaching grammar, actually. Yes, it might help to have a more organized grammar reference, but Duolingo does make you practice grammar quite efficiently in my experience. For those complaining about Duolingo: Are there better routes? The convenience of the app, integrating audio, grammar and vocabulary are really hard to beat in terms of learning efficiency, even if you might have an in-person course.