Eli B Toresen is the international editor in chief for Stabenfeldt’s Pony Club division, based in Norway. She spends half her week working as an editor, and the rest writing her own books. Her output is pretty phenomenal: she writes four books a year. I would guess that not all of them are translated into English.
She has written several books that have just appeared as CDs: an interesting hint about where publishing might go.
Finding the books
No Stabenfeldt titles were published in the UK, but some copies have been imported and are usually available fairly cheaply here. Alternatively, you can try American sites, or Ebay.com, where bundles of titles tend to come up fairly often.
Links and sources
An interview with Eli B Toresen