Dear User, as isomers are a hard to explain part of Organic Chemistry, and I need a sources page, I'll use this opportunity to do the sources page and ignore isomers. If You feel like You have been cheated out of Your well-merited isomers tutorial, please contact me at notreal@notrealmail.com . https://www.makeuseof.com/tag/ build-simple-php-website/amp/ dev.gyre.ch https://codepen.io/s-ammar/pen/JOYdje https://www.freecodecamp.org/news/multiple-choice-quiz-templates/amp/ https://www.w3.org/ 2002/01/spellchecker . I am also very aware that the multiple choice quizzes may not work, but as I tried spellchecking it, and it said there is no problem with the code, I have honestly no idea as to why it would not work