Reddit mentions of Illustrated Signs and Symbols Sourcebook An a to Z Compendium of over 1000 Designs

By the by, you might really enjoy this book if you love symbols (as do I):

https://www.amazon.com/Illustrated-Symbols-Sourcebook-Compendium-Designs/dp/1435126378/ref=sr_1_1?s=books&ie=UTF8&qid=1467852886&sr=1-1&keywords=adele+nozedar

/r/whatisthisthing may be able to help you too. I'm not too informed on astrological symbolism, sorry. :C

If you still go to the library (like anyone does THAT anymore), check out the book The Signs and Symbols Sourcebook. It may help you uncover some of the symbolic meaning.

I have this book and I love it: The Illustrated Signs and Symbols Sourcebook https://www.amazon.com/Illustrated-Symbols-Sourcebook-Compendium-Designs/dp/1435126378/ref=sr_1_1?s=digital-text&ie=UTF8&qid=1482896151&sr=8-1&keywords=signs+and+symbols+sourcebook

very comprehensive with different alphabet systems, animals, deities, plants, runes, geometry, minerals, tarot, freemasonry, etc -- there's a 10-page "Further Reading" section in the back but it's not really laid out so it's easy to read the entry for the item and then link that info to the source it's from, you would just have to read through the list of titles individually to see which ones might have more info about the subject you want