If you have a set of books in the same series, you need to contact KDP to request they setup a single sales page (and buy button) for the entire series like this:
But first, you need to update the metadata in your bookshelf! Here's the step by step. If you prefer a video tutorial, jump to the end.
Make a note of your ASINs:
Submit a request to KDP via the Contact Us link at the bottom of the page:
Provide the info for your series (with ASINs):
Here's the actual note I sent:
Dear KDP, Can you please create a series page for these 2 titles? Select type of request: Create Series Collection 1. Add ASIN: B0039IT0TW - Book 1 2. Add ASIN: B003UNLIO6 - Book 2 Thank you.
It'll take 24-48 hours and they'll usually confirm via email. When it is live, you'll have a new ASIN to link to (in this case B01M3177EJ). Reviewers can post reviews for the entire series and you'll gain greater visibility on Amazon:
Don't forget this final step! It does require you have a Author Central account.
Once you've done this for your own series, share a link to it in the comments below!