Irish author Seamus Heaney is among several authors whose appearances at the Edinburgh Book Festival have led to a record demand for tickets.
Seamus Heaney is considered one of Ireland's greatest writers
Two events with the Nobel Prize-winning author have sold out and 25% of all tickets have been sold in three days.
Appearances by Scottish authors Ian Rankin and Alexander McCall Smith have also sold out.
The book festival runs along with other Edinburgh festivals in August, which attract thousands to the city.
Other guests at this year's event include poet laureate Andrew Motion, British playwright Harold Pinter and Irish novelist Roddy Doyle.
Doyle joins authors such as Antonia Fraser, Kate Atkinson and Simon Schama in launching his new book at the festival.
More than 200 Scottish authors will also take part in the festival, which is held from 12-28 August.
This year will also see a series of special events held in October, with speeches from Chancellor Gordon Brown and novelists Martin Amis, Margaret Atwood and William Boyd.
Organisers say they sold 36,000 tickets in the first three days of booking for this summer's festival - up 54% compared with the same period last year.