My intention is to make this book freely available to everyone. If you wish to support this work, you can do so by donating to help children and people affected by disasters in war-torn countries through the International Committee of the Red Cross (ICRC). For details, see Supporting this work.

Writing this book is one of my bucket list items. I hope it will be of some benefit to students, teachers, researchers, and anyone interested in this field. I compiled the contents based on my own understanding; if you find any mistakes or have any suggestions, please feel free to let me know :) Happy reading!

Last updated: December 21, 2022