I do mine manually. I just do a word document by author name, then shortened titles after it. You still have to watch out for authors that republish books in another name (Kathy Hogan Trocheck now out under Mary Kay Andrews is a good example). That way I just print one page off and take it with me, and I can write new additions on it to update later. And if you want to get really picky, I also have a Wish List of items coming out I want or order, or hardbacks I want to order when the paperback comes out.
I am building a custom website to manage my books, but one tool that has been helpful is Calibre.
This is really eBook managing software. It's free.
What I have done for the paper books is just save a .txt file that includes the name of the book and the author. I can then import the .txt file into Calibre as if it were an eBook.
Once I import it to Calibre, I use Calibre to record metadata (author, publisher, genre tags, etc). Just ignore the links to open the "book," since it will only open that nearly empty .txt document.
I have this installed on my laptop. They say there is an online content server, but I haven't looked at it since I am building my own site so I have some specific custom features/capabilities other software won't provide.
I like goodreads. I've done the same thing on my kindle--buying a book I already read. Luckily, they're really good about refunding. But I do the same thing at the airport...more frequently than I'd care to admit. I read so much that I just forget!
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I sort mine the old fashioned way. I have a spiral notebook that I write my books in by author. I then have a mini little flip spiral that I write the ones I don't have in by author.
I put the mini notebook in my purse so if I stop at our used bookstore or place lake goodwill or SA I can skim through the notebook if I find a book. When I do get home I cross it out of the mini one and write it in the big one. This has saved me from buying duplicates alot. I even take it with me when I garage sale.
As a sometime librarian with a master's in library service I'd say use Excel. You can list them by author, title, publisher, call number (invent your own system if you don't like Dewey or LC), date, color, size, whatever, and then sort by any of those to find the ones you want.
Or just do it in your head and shelve them by subject or alphabetically by author's last name.
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