Analysis of N-acetyl-4-O-acetylneuraminic-acid-containing N-linked carbohydrate chains released by peptide-N4-(N-acetyl-p-glucosaminyl) asparagine amidase F. Application to the structure determination of the carbohydrate chains of equine fibrinogen - Damm, J BL; Voshol, H; Hard, K; Kamerling, J P; Vliegenthart, J FG (Eur J Biochem, 1989)