Wood toxicity, allergies and database.
A comprehensive guide with more information than anyone is likely to need but well worth the trouble of referencing woods that you are likely to use. It is written in a no nonsense and understandable way.
Also have a look at some of the articles past the database.
Credits are to Eric Meier who has published a book called WOOD full of information.
On our clubs doorstep at unit 44, Taylors supplies high class pen kits, pen blanks, woodturning blanks, tools, wood blanks, sanding sheets, Charnwood power tools and accessories, Chestnut finishes etc, Dan is very helpful and so don't feel you have a silly question.