In 2016, the KB contained 7,000,000 items, equivalent to 115 kilometers of bookshelves. Most items in the collection are books. There are also pieces of "grey literature", where the author, publisher, or date may not be apparent but the document has cultural or intellectual significance. The collection contains almost the entire literature of the Netherlands, from medieval manuscripts to modern scientific publications. As there was no law for depositing Dutch publication the library started on January 1 1974 the voluntary . This in contrast with most other countries that have a legal deposit of publications. For a publication to be accepted, it must be from a registered Dutch publisher. 