2017 is the 50^th anniversary of the publication of the first of John Christopher’s Tripods books, The White Mountains, and while the books have already been available in the UK for several years in digital format, Penguin marked the occasion by bringing out a new paperback edition:

In France, Ecole des Loisirs has just brought out an omnibus edition of the first three books (The White Mountains, The City of Gold & Lead, The Pool of Fire) …

… whilst in Germany, Piper Verlag jumped the anniversary gun by publishing in 2016 an edition which brings together all four books (i.e. including When the Tripods Came):

The Tripods books are also available in Spanish …

… and in Chinese: