I have a book called "Two-Hour Dolls Clothes" by Anita Louise Crane. It has patterns for several outfits for 12, 14, 16 and 18 inch dolls and sewing instructions. Of course the patterns don't fit bears but it gave me an idea for the basic pattern piece shapes so I go from there and draw the patterns out to my bears' measurements.
Chrissie, there is a book called The Doll's Dressmaker. I think it is out of print, but you can get copies on ebay, often from the UK. It explains pattern design for doll clothes and has some patterns. You can use the same instructions with bears, because its about measuring and adapting the shape of the garment to the shape of the doll/bear.