About Addendum

 Hello, and welcome to Addendum Books! We are an independently owned bookstore in St. Paul, Minnesota. We specialize in young adult literature, though we also carry many wonderful middle grade and picture books

We are:

Marcus Mayer, co-owner

Marcus worked as a librarian and a teacher, as well as a bookseller at three independent bookstores in the Twin Cities, before opening Addendum. Marcus has been involved with various children's and young adult literature awards committees and boards, including the Kerlan and the Minnesota Book Award for both the Children's Literature and Young People's Literature categories. He is currently on the board for the Minnesota Youth Reading Award as part of the new Star of the North picture book award. When Marcus isn't working you will find him reading, running, or writing. 

Special thanks to Studio 306 for the photo.
Katherine Warde, co-owner
Katherine has her master's degree in elementary education, and worked as a teacher, tutor, and nanny (among other jobs) before opening Addendum.  She owns her own photography business, and does most of the event photos for the store. Her photographs have appeared in such publications as Publishers Weekly, Shelf Awareness, and School Library Journal.  When she's not working, crafting, or behind the camera, you will pretty much always find her with her nose in a book.  

If you would like to use any of our event photos, please email us at: addendumbooks [at] gmail [dot] com. Thank you!


  1. Thanks so much for your efforts on behalf of the event in Red Wing. It was great fun to meet you both and I look forward to more stories from the Indy Book Store front lines. Best of luck and I loo forward to visiting on my next visit!
    -Mark Fearing

  2. Keep driving by waiting to see you in the new store and lavish you with neighbor-gifts. Best of luck getting books on those shelves soon!

  3. Hi guys!

    I'm a local Cartoonist and creator of the syndicated comic strip Best In Show. I've recently written a children's chapter book based on the characters and I'm in the process of marketing it. I just discovered your bookstore and had to contact you! Would you be willing to have a look at a copy in consideration for a space on your Local Authors shelf? I would love to send a PDF copy for your review as the hard copies are in production (and should be in hand soon!) Please let me know your thoughts!

    Thanks so much!

    Phil Juliano
    Cartoonist and Humorous Illustrator