Add some more info

[Grancpol]

Some more info (cover, description in Polish etc.) can be found here:
http://sklep.gwfoksal.pl/dziecko-wojn... - publisher
or here:
https://www.amazon.co.uk/Dziecko-wojn... - amazon

[Arenda]

The complete edition (with isbn and cover) is already here: https://www.goodreads.com/book/show/3...
I've queued the duplicate for merging.

There are some differences between Goodreads, Amazon and the publisher.
Amazon has paperback, January 2015
Goodreads has hardcover March 2016
Publisher has hardcover, no date.
All for isbn 9788328026049

[Grancpol]

The book was released on 13th April 2016. Originally was supposed to be 30th March.
Polish edition only hardcover as far as I know.