Textbook
Interaction Design: Beyond Human-Computer Interaction, 5th Edition (e-version, SMU library, pdf)
Helen Sharp, Jennifer Preece, Yvonne Rogers ISBN: 978-1-119-54730-3 April 2019 656 Pages
The Design Thinking Toolbox: A Guide to Mastering the Most Popular and Valuable Innovation Methods (Design Thinking Series) (website, pdf)
April 14, 2020 by Michael Lewrick, Patrick Link, Larry Leifer
Certification
In the UX industry, experience matters more than certification. However, if you are interested, Here are some options:
Google UX Design Online Certification (Video, Coursera 7 days, SMU extend email Mok Heng Ngee)
Nielsen Norman Group In-Person UX Certification (Process, Location)
CareerFoundry Online UX Design Program (free beginners, user research)
General Assembly UX Design Immersive (Singapore)