Books, e-books, journals, e-journals, databases, DVDs… Getting the balance right

Looking back it is possible to see some major patterns of change in the
purchase of resources for an academic library. One significant change
is in the move from predominantly one-off purchase in many areas
(journals, books, reference books, music and film) to ongoing or multiyear
commitments for many types of resource. Many libraries might,
for example, have bought some reference books every other year
quite happily, but now they might need to decide each year whether to
subscribe or not.