First of all, I want to say thank you to all of the authors of work released under open and free licenses I have used to produce The Polish Language Stuff resources. Special thanks go to: Steve Kaufmann, the author of the original English version of The Linguist and Piotr Kowalczyk, the author of Hasło Niepoprawne.
To create image indicators of language level, placed next to each title of any content item, I used icons from androidicons.com.
Also, I’d like to say thank you to all of you who helped me improve my written English. Special thanks go to: Carmen, Chris, David, Josh and Larson.