ReadWorks has now added illustrated eBooks to their collections. (click here for a link from ReadWorks about their eBooks). Simply select eBooks underneath Curriculum & Supports and then assign as you typically would to your class (class or Google Classroom).
When students see the article assigned to them, they will need to select eBook at the top of the article.
Embedded below is a 1 minute and 9 second YouTube tutorial followed by previous blog posts about ReadWorks.