Find replacement for Sage entities in pdf?

[kcrisman]

"If you are not already reading this in an electronic version, you may want to investigate obtaining the worksheet version of this book, where the examples are “live” and editable."

But this statement isn't even in the tablet version. Not sure how to deal with this, but probably there should be something at places like "Sage M" in print that mention it would be there in the online. Obviously low priority and big picture.