Norway Farm Books or Bygdebøker
Norway Farm Books (often referred to as: Norwegian Farm Books)
Norwegians (outside of cities) lived in communities called "bygd" which really were small towns and villages. Norwegian Farm Books contain histories of these bygds, their families, and their communities. There is a surprising amount of information contained in them about families who lived in these communities, sometimes they list parishes that families have come from as well as where they move to. They have been transcribed from the original manuscripts and can be found in book form now...although they are not yet translated into English. There is an extraction program underway to extract the information from these farm books.
Throughout Scandinavia, including Norway, the "patronymic" naming system was used; meaning the last names would end in "sen" or "datter". Today most Norwegians use "family names" or set names. That would mean a patronymic name or a farm name being used as a surname. If a Norwegian surname does not end in "sen" it could be a farm name, and that could be a clue to help you locate their place of residence.
Finding the parish where the farm was located will tell you where the family records can be found.