2.4.1.1. Video: P vs B | English Pronunciation Lesson - YouTube - https://www.youtube.com/watch?v=3k7jN4kX4U

2.4.1.2. Video: Minimal Pairs: /p/ vs /b/ - YouTube - https://www.youtube.com/watch?v=9kX4kC1L9X0I

2.4.1.3. Article: Minimal Pair /p/ and /b/ | Learn English - https://www.englishclub.com/pronunciation/minimal-pairs-p-b.php

2.4.1.4. Article: English Pronunciation: /p/ vs /b/ - Pronunciation Studio - https://pronunciationstudio.com/p-b/