The Vintage Shirt Company, for classic stiff collars.
Town and Country Flowers, perfect for buttonholes.
Hat Works - Hat museum, England
Atelier-Musée du chapeau - Hat museum, France
Hut-Museum Brömme - Hat museum, Germany
Emperor Franz Joseph - Hat museum, Austria
Alyce Cornyn-Selby - Hat museum, USA
The Sterling Beaver - Hatters Forum