2.3.2.1. Video: S vs Z | English Pronunciation Lesson - YouTube - https://www.youtube.com/watch?v=7eA6fN2vO4U

2.3.2.2. Video: Minimal Pairs: /s/ vs /z/ - YouTube - https://www.youtube.com/watch?v=zvM3TUo4r2o

2.3.2.3. Article: Minimal Pair /s/ and /z/ | Learn English - https://www.englishclub.com/pronunciation/minimal-pairs-s-z.php

2.3.2.4. Article: English Pronunciation: /s/ vs /z/ - Pronunciation Studio - https://pronunciationstudio.com/s-z/