There's always a recommendation or two regarding a particular whitepaper that you should read in order to pass the AWS Certified Solutions Architect - Associate exam.
Be careful. Some whitepapers are not written for a wide technical audience. Instead they are focused on a particular solution, and typically an advanced solution.
Advanced solutions are not what the Architect - Associate certification requires. For example reading the whitepaper Designing Next Generation Vehicle Communication with AWS IoT Core and MQTT may be interesting, however this paper has nothing to do with the exam we are focusing on.
And although there are certainly good reasons to use whitepapers as a source of knowledge for the exam, there are also some technical documents called a decision guide that are also worth reading. Decision guides can be found here.
A caution. Make sure that the date of any technical documentation is within two years of the current year otherwise the technical information my be out of date.
It’s easy to forget to verify the publishing date before you begin digging in to a technical document.
Always read the latest and greatest.
Start with This Whitepaper
There are whitepapers that are aimed at a general technical audience such as this recommended whitepaper: Overview of Amazon Web Services.
Under AWS Services, the sections that are relevant for our exam are: Analytics, Application Integration, Cloud Financial Management, Compute, Containers, Databases, Management and Governance, Network and Content delivery, Security, Identity and compliance, and Storage.
Each link as shown in the Storage example below will point to additional relevant documents, white papers, and videos.

Finally, checkout the Resources link. There’s a wealth of resources that are great for the Architect - Associate exam.
AWS Decision Guides - Excellent focused documentation that compares and contrasts the options available for cloud architects. For example: Choosing an AWS Storage Service. There are many other decision guides that are referenced throughout the whitepaper.
AWS Architecture Center - A resource that presents various AWS architecture deployment examples. Take a look at Scale Out Computing on AWS for an interesting walkthrough on deploying a multiuser environment complete with operational step-by-step details.
AWS Documentation - Deployment details for every AWS service can be found here. AWS documentation can be overwhelming, however, the documentation is always up to date. Step-by step walkthroughs and all the details can be found here.
AWS Blog - Not every blog post will be relevant, but several are relevant to the Architect - Associate exam such as Architecture, Compute, Containers and others.
Don’t Forget This Whitepaper
Finally, the white paper I would recommend starting to read, and keeping close as a resource is the AWS Well-Architected Framework document. It’s likely that this document will save you from reading the Security, Performance efficiency, Reliability, and Cost optimization documents.
Open the link to the Appendix: Questions and best practices. Each pillar that the Architect - Associate exam is based on will have a list of questions to consider, and best practise solutions to consider.
For example the SEC 5 question: How do you protect your network resources?
There are eleven Security pillar questions to review.
There are thirteen Reliability questions to review.
There are five Performance efficiency questions to review.
There are eleven Cost optimization questions to review.
Kind of like best practise exam of 40 questions if you think about it.
Happy reading!
Next up: What Well-Architected Labs to do.