The newer non-fiction/science books are generally not on the data base, so I have to add them. I use the shelve-it feature and amazon.co.uk as a short-cut.
How does the shelve it feature work? For a while I was trying to find books by ISBN because they seem to come up that way even when they don't by title/author, but I got frustrated with having to add books.
From the dropdown menu on the dashboard you select shelves. There is a black and white globe looking icon in the headings section somewhere. You drag that icon to your web-browswer title bar. Then you go to the amazon.co.uk (has to be the uk amazon) site for your particular book and click the little globe thingy in your title bar. You should end up with a BL page that has all the relevant info. You just need to edit it. You need to put the cover picture in (might want to copy and save that off the amazon page) and fix the ISBN/ASIN issue (it puts both, not just one). Voila!
I've only read the first book of the series so far ("The Colour of Poison" -- all the titles have a "colour" theme, because the hero is an illuminator by trade). I liked it and am planning to continue the series, though it's been a while now since I read it.