Just found out that one of my favourite knitting books (published in the 80s) is available to read for free online! It's very difficult to get hold of - I am lucky to have my grandmother's copy. The book, written by Vibeke Lind, was translated into English as "Knitting in the Nordic Tradition" but I guess those copies are just as difficult to find.
The online version is in the original Danish, but it actually doesn't matter much if you don't know a word of the language: the book is a great collection of charts, mostly for stranded colourwork.
And there are wonderful old photos of people knitting and/or wearing knitted garments.
Hope you find it useful!