Some key requirements in API Specification 6A, 21st Edition, include:
The is the latest major revision, and it brings the industry into a new era of modern material science and manufacturing technology. api specification 6a 21st edition pdf link
While the full standard is paid, API provides free access to critical updates, errata, and addenda: Some key requirements in API Specification 6A, 21st
Additionally, mentioning that some institutions or libraries might provide access if the user is affiliated with an educational institution or a company that has subscriptions could be helpful. Also, advising them to contact API directly for details on pricing and purchasing steps is important. Maybe include a link to the API standards page so they can navigate there themselves. Maybe include a link to the API standards
However, here is a of what to expect from the 21st edition of API Spec 6A, along with guidance on legitimate access.