The 6th print edition was released in February 2015, based on content that is now 4 years old.
In the meantime there have been more than 1500 significant revisions made to the online version, but the print edition has not changed.
This means that the 6th print edition is now not as up to date as we would like in quite a few areas.
For this reason we have decided to retire the the 6th edition of the print edition and withdraw it from sale.
In the following months we will decide if there will be a 7th print edition – but if there is, it will not be released before July 2019 at least.