- http://dictionary.reference.com/browse/liberal
 - https://www.vocabulary.com/dictionary/liberal
 - https://www.studentnewsdaily.com/conservative-vs-liberal-beliefs/
 - http://www.merriam-webster.com/dictionary/liberal
 - https://ru.wikipedia.org/wiki/Либерализм
 - https://en.wikipedia.org/wiki/Liberal