When you see a Calendula 90% tincture in a blend, it means that it was extracted with a higher alcohol percentage to extract the anti-fungal properties. You will see either Calendula 25% (for anti-viral) and Calendula 90% (for anti-fungal/anti-bacterial) applications.
That book in particular could probably be ordered online – I have seen it on Mountain Rose Herbs and Amazon. There is also good information in Pacific Northwest Medicine Plants by Scott Kloos. (identification, harvesting and making medicines). Where do you live? If in the local Victoria area, I am sure some local herb shops and book stores might carry that one.