Organizing Bookshelves

The last two days, I've been doing something I haven't done for a long time: completely reorganize my bookshelves. I'm finding books I forgot I had. I'm finding duplicates too: two copies each of Paul Horgan's 'Great River', Douglas Preston's 'Cities of Gold', and Ferenc Szasz's 'The Day The Sun Rose Twice'. Plus, I apparently can't pass by a biography of Nikola Tesla in the bookstore without buying it.