The iBooks of Walking in the Footsteps of Odysseus and The Excavation at Agios Athanasios will be available for free between 4pm Pacific Daylight Time today 19th April and 4pm PDT 23rd April from Amazon UK or US. The walks book has been updated this year. All can be read on a free download of the Kindle app. All three books are available in paperback format from Amazon worldwide. For those it is best to order from your most local Amazon, whether that is in the UK, US, Australia, Italy, Canada, Japan or Brazil (etc.) as they print on demand in those places.
