The world's smallest book just one millimetre square is among a number of unusual volumes on display at Aberystwyth to mark World Book Day.
The smallest book is displayed within the circle
Old King Cole, a 12-page book of the famous nursery rhyme, is part of an exhibition at The National Library of Wales at Aberystwyth.
The miniscule volume is one of only 85 copies printed by Scottish publishers in 1985 and can only be read using a microscope.
Among the other rare books on public view are the oldest book printed using moveable type in the 15th Century, the first printed book in Welsh, and also the smallest book in Welsh.
Sion Jobbins, marketing officer at the library, said the books would be on display for the next two weeks.
"We wanted to show the breadth of the library's collection as well as providing an introduction to the library's facilities," he added.
The National Library has the right to keep every book printed in Britain and Ireland and currently has more than 4,500,000 volumes.
The smallest book in Welsh is a selection of hymns given as prizes to Sunday school children in the 1830s and measures just 44mm by 33mm.
The first printed book in Welsh was made in London in the early 16th Century and includes translations of The Lord's Prayer and the Ten Commandments.
The library also houses The Bull of Pope Pius II which is the earliest book to be printed using movable type at about 1470..
Other unusual attractions in the exhibition includes a religious book printed by William Caxton, England's first printer.