2. General: "Thermoplastic Polyolefins (TPOs) in Roofing Applications" - this is a very good short introductory article available on the SPRI website.
3. Chemical Compatibility of TPO: See this Chemical Resistance Guide for information about whether a substance will damage a TPO roof. The document is on the website of Roofing Products International.
4. Inspection of TPO Roof Systems: "TPO (Thermoplastic) Rooftop Guide/Inspection Checklist" is a handy two-page document put together by Carlisle Syntec Systems. It references Carlisle products, but it's broadly applicable to other TPO systems.
8. Testing: "Testing TPO (An unprecedented study shows surprising variations among TPO membranes" explores TPO performance issues. The article appeared in Professional Roofing magazine in 2015 and is available on the GAF website.