2. Built-up Roofs: "Ways to Reduce Blistering in Built-Up Roofs" is a short, informative article available at the National Research Council Canada website. It includes a good explanation of how blisters form in built-up roofs.
3. Modified Bitumen: "Blistering in SBS Polymer Modified Bituminous Roofs" is a terrific article, also available on the National Research Council Canada website.
4. Modified Bitumen: "Investigating the Cause of Blistering in SBS Polymer Modified-Bitumen Roofing Membranes" is heavy on technical detail and explanation of methodology; scroll to the end for the conclusions if you're short on time. Available on the National Research Council Canada website.
5. Shingles: "Blistering of Asphalt Shingles" is a short technical bulletin available at the website of the Canadian Asphalt Shingle Manufacturers' Association.
6. Spray Polyurethane Foam: "Spray Polyurethane Foam Blisters - Their Causes, Types, Prevention and Repair" is a concise, authoritative article produced by the Spray Polyurethane Foam Alliance and available on the website of NCFI Polyurethanes.