Finna.fi is a search service that collects material from hundreds of Finnish organisations under one roof. Using versatile search functions, you can easily access millions of items, among them more than 10,000 books as well as textbooks / OER.
Hundreds of Finnish archives, libraries (both public and HEIs), museums and other organisations have offered their cultural and scientific treasures to be found in Finna.
Finna.fi provides access via an open API, see https://api.finna.fi/swagger-ui/?url=%2Fapi%2Fv1%3Fswagger