1910-1914 is known as Early Teens, Late Edwardian, Titanic, Early Automobile, pre-World War 1, and it was represented by Season 1 of Downtown Abbey.
Vintage Victorian has a lovely overview of clothing of the period.
A search of Pinterest for “1912 Fashion”
Menswear, including “how to fake it”
Womenswear, including “how to fake it”
Early Teens patterns:
Gowns of Queen Maud of Norway, c. 1910. Style & Splendour
Hats:
Books:
- Everyday Fashions 1909-1920
- Edwardian Ladies Hat Fashions
- Style & Splendour: The Wardrobe of Queen Maude of Norway