Manufacturers links:
The Cedar Bureau
https://www.cedarbureau.org/installation/roof-installation-manual/
Cedar Valley Technical Documents:
https://cedar-valley.com/technical/code-and-technical-appendix/
Cedarwood Products:
https://www.cedarwoodproducts.net/for-installers/installation-guides/
SBC Cedar
DaVinci Shake
http://www.davinciroofscapes.com/wp-content/uploads/2018/11/Shake-Installation-Guide.pdf