Section: 3.1 Chyptographic Measures
Question: At the beginning of this section the document talks about related documents. About the guideline for information classification and about contractual and legal needs. About the second one: by this do you mean the list of legal, official, contractual and other requirements? If yes do I have to add the document in section 2 (reference documents)?
Yes, the referred document is the list of legal, official, contractual and other requirements. Regarding the second, you have to list this document, or the similar one you already use in your organization, in the list of referenced documents. If you don't have such a List, then list all the legislation and contracts related to the use of cryptography.