https://www.inverse.com/article/32786-duolingo-preserve-extinct-endangered-languages
The Duolingo App is Keeping Endangered Languages from Going Extinct
Jun 23, 2017 - One app can't fix the problem, but Duolingo is making a difference.
duolingo appendangered languageskeepinggoingextinct
https://testprepinsight.com/comparisons/babbel-vs-duolingo/
Babbel vs Duolingo | Which App Is More Effective? | Test Prep Insight
Jul 17, 2026 - We compare Babbel and Duolingo in terms of pricing, pros and cons, and which one helps you build real conversation skills.
app ismore effectivetest prepbabbelduolingo