Anjali,
The only way to obtain the documents / study materials (as well as being the best way to prepare!) is to take the relevant training from Beyond. In the case of Core, that is "CIC Administration" and "Configuring Call Flows".
Both of these are available as self-study or Instructor-Led. They also form part of the ICCS Intensive class, if you are continuing to that certification.
Any official materials you obtain that do not come directly from Beyond are probably pirated and, given that this is an official Genesys forum.....!
Further details on these classes can be found
here and
here, whilst details on the Intensive class are available
here.
HTH