The 10 bestselling books on AbeBooks.com during May:

1. The Soloist by Steve Lopez
2. Angels and Demons by Dan Brown
3. Atlas Shrugged by Ayn Rand
4. The Origin of Species by Charles Darwin
5. The Five Love Languages by Gary Chapman
6. Michael Recycle by Bethel Ellie
7. The Great Gatsby by F. Scott Fitzgerald
8. The Selected Works of T.S. Spivet by Reif Larsen
9. The Civil War by Geoffrey Ward
10. Jesus Calling by Sarah Young
 
The 10 bestselling signed books on AbeBooks.com during May:

1. The Selected Works of T.S. Spivet by Reif Larsen
2. The Angel's Game by Carlos Ruiz Zafon
3. The Sweetness at the Bottom of the Pie by Alan Bradley
4. The Enchantress of Florence by Salman Rushdie
5. Everything Ravaged, Everything Burned by Wells Tower
6. The World's Wife by Carol Ann Duffy
7. Brooklyn by Colm Toibin
8. The Children's Book by A.S. Byatt
9. Walking the Perfect Square by Reed Farrel Coleman
10. Drood by Dan Simmons

[Many thanks to AbeBooks.com!]