I am usually full of praise for the mass digitisation of cultural heritage led by the #NationalLibraryOfNorway.
However, the #OCR of the newspapers' full text is abysmal.
When I search for "ex libris", I have learned to do it by looking for "ex" – a seldom-used word in Norwegian – & manually checking.
Some examples of what a simple search for "ex" yields. In combination with "libris", the latter word is almost always misread.
80% of the time, ex is the misread version of "er" (= is).