I have an indesign book with 9 docs, total 240 pages. Is it possible to work with it?

Question

Or Have I to convert them in one only doc?

Any recommendations about how to work with bigs docs?

Answer 1

You could either convert the multiple docs into one doc with the MergeFiles script or make a main document, export the other documents separately, and link from the main document to the individual ones.

Here's an article with Tips & Best Practices for Exporting Long-from Digital Documents from InDesign with in5 (and speeding up load time).