To all the authors out there struggling to promote sales of their books on multiple sites, Draft2Digital just released a feature called Universal Linking that helps with this chore. The concept is simple. Instead of trying to advertise multiple links for all the sites that sell your books, you can use the single universal link created by Draft2Digital to direct the reader to a page on the Books2Read site that links directly to your books on all the selling sites. I suppose it's one extra click for readers, but I prefer that one extra click versus all the extra text and links that would be necessary in a snippet of ad copy to showcase all the places to purchase the book.
I'm not sure about other authors' methods, but I know I usually focus on only advertising a single venue, such as Amazon, per piece of ad copy in order to keep it polished and professional. This will allow me to create ads that provide easy access to all the selling venues without a lot of convoluted wording, and I'm looking forward to trying it. I already work with Draft2Digital for some of my digital publishing, so they created my universal links automatically, and I just had to add links for the other vendors they don't handle. If you don't already work with D2D, I think you can still create universal links for your books, or at least that's my understanding from reading the email they sent out. My interpretation is you just have to set it up yourself on Books2Read.com.
These are what my universal links and landing pages look like:
Defying a Duke: https://www.books2read.com/u/bP87rb
Mystery Lady: https://www.books2read.com/u/47kMkR
I hope this info helps some other authors out there. Pass it on!