Wood Shingles and Shakes
1. Maintenance and cleaning: "Care and Maintenance of Wood Shingle and Shake Roofs" goes into a decent amount of detail. The article can be found on Oregon State University's Oregon Wood Innovation Center's site.
2. Technical: Installation guide: see this roof manual page for access to extensive construction details that show what's going on (or should be going on) in a wood shake or shingle roof. Provided by the Cedar Shake and Shingle Bureau.
3. Technical: See this Product Data Sheet for the technical characteristics of cedar shakes and shingles at the website of the Cedar Shake and Shingle Bureau. This is only an example and other products and brands may be different.
4. Technical: "The Repair and Replacement of Historic Wooden Shingle Roofs" is an excellent article available on the US National Park Service's Technical Preservation Services website.