The total growth of published knowledge in the form of books, periodicals, documents and other knowledge services such as data bank output, and the increasing cost of each of these, combine to make the total cost of knowledge increasingly excessive. Many important reference sources and periodicals can only be purchased by institutions, and often only by institutions to which the public does not have access. This is true of developed as well as developing countries, and is especially true of the reference tools without which relevant documents cannot be efficiently located.
As an example, estimates in the UK of increases in non-fiction book prices give an average of 15.4% per year for the 1960s. In some years prices increased by nearly 20% for adult non-fiction.