- The Closed Collections are accessible Monday to Friday, 9:00 a.m. - 15:00 p.m.
- The reader does not have access to the shelves. The books are fetched from the stacks by the appointed officials.
- The books in this area, with the exception of the Rare Classified Books and the books of the Athanasiadis Collection, do not follow the LC classification scheme, as do the open collections. The Call Numbers of most collections consist of three letters, which encode the name of the former owner of the collection, and the number of the Book Εntry in the Library. For example: PPK 112345 = Papakosta Collection Book with entry number 112345.
- The material of the Closed Collections is non-circulating and can be read only in the reading room within this space, under the supervision of the library staff. Exceptions are made only for twenty-four hours for books of the 20th century, for professors and postgraduate students, as long as the staff in charge deems that the book can be borrowed.
- For books printed before 1930 photocopying is strictly prohibited. Newer editions are photocopied only when photocopying does not compromise the integrity of the original.
- Material that can not be photocopied but has been processed can be made available, at the request of the reader, in microfilm or digital format.
- All books to be used in the following days are delivered to the employee, who activates the reservation for as many days as the user suggests.
- The reader of the Closed Collections can request and use up to five books.