is it allowed to use software?

Hello,

my question is: is it possible to use books and/or software to play the multi-day tournments (1, 2 or 3 days )?

many thanks

antonio

You can use printed and online books and computer databases.  However, databases that compute engine recommendations would not be allowed. Computer engine use is not allowed.

Helle many thanks for your answer. This rule is written somewhere? I ask because some chess societies allow to use software

What you mean by "using software" is unclear. As I said, certain types of computer assistance are allowed. Others aren't. This is from the Help section:

No Cheating or Computer Help

You can NEVER use chess programs (Chessmaster, Fritz, etc) to analyze current ongoing games unless specifically permitted (such as a computer tournament, etc). The only type of computer assistance allowed is games databases for opening lines in Turn-based Chess and Vote Chess. You cannot receive ANY outside assistance on Live Chess games.

Helle,

IT has to use software, that's kinda how it works!

Do you mean computer engines?   If so, NO!!!!   It will be considered cheating.

The official rules are here: Terms & Privacy (link at the bottom of every page). More details can be found here: Fair Play on Chess.com: What you Need to Know You can get there via the Help link at the bottom of each page.