Floris Books in Great Britain has a great selection of the classic Swedish authors translated into english. Since their page isn't very user friendly I've made a selection of links below. The english editions are also available in Sweden through Adlibris.com, in Norway in through Norli.no, and in the US through Amazon.com.
The tomte's christmas porridge, by Sven Nordqvist.
Books by Elsa Beskow are available both in regular size and mini editions.