These are some of the online archives and collections of vintage patterns and tutorials that I’ve found useful. There are a number of blogs and websites dedicated to vintage crafting that I’ve listed here too. Many of these blogs have their own resource lists and links to other sites for advice, tutorials etc.
The V&A – resource lists and patterns for knitting and dressmaking
Subversive Femme – vintage knitting patterns
Tuppence Ha’penny – vintage fashion and dressmaking
Fabulous Forties – knitting and sewing patterns for sale
Free Vintage Knitting – exactly that
Vintage Chic – vintage fashions and knitting patterns
Historic Knitting Music – strange but wonderful
Art of Mourning – mostly 19th century mourning clothes and jewellery
University of Southampton – Jane Waller Collection – knitting reference materials, patterns and history of knitting
Archive.org – digitized version of books including A Complete Course in Millinery, The Little Girl’s Sewing Book, The Science of Knitting, and The National Garment Cutter Book of Diagrams. It is a huge digital archive and sometimes it can be a little overwhelming but some patient searching will yield results. A similarly enormous collection (with some overlap) is The Online Books Page.