If you already have a Kobo account, you can link your Kobo and bol.com accounts by following the steps in this article.

To sign in using your bol.com account on Kobo, simply choose the My bol.com account sign-in option, and sign in with the same username and password you use for bol.com.

When the accounts are linked,  you will see all your books in one library. If your Kobo account and your bol.com account use the same email address, you must sign in with your Kobo account first.

1. Go to Kobo.com.
2. Click Sign in at the top of the screen.
3. Enter your bol.com account username.
   If a message appears that says that your email is linked to an existing Kobo account, you will be redirected to sign in with that account. Enter your existing Kobo password.
4. Click Continue. 
   You'll sign in to the Kobo website and be redirected to the home page.
5. Click My Account at the top of the screen.
6. Click Account Settings.
7. Scroll down to the Sign In Options on the left side of the page.
8. Find My bol.com Account from the list click Link this account.

Once you've linked your account with Kobo, you can continue to use your existing bol.com account to sign in to Kobo.