Bing Wang, Patricia McVeagh, Peter Petocz and Jennie Brand-Miller (2003) Brain ganglioside and glycoprotein sialic acid in breastfed compared with formula-fed infants. American Society for Clinical Nutrition 78: 1024-9.
As far as I know Sialic acid glycoproteins are found on the surface of various cells but dont quote me on that one.
has a small description with a journal citation. I would think you couldn’t help but find something in a standard biochemistry textbook, if it’s any good anyway. Look under things like "glycosylation" probably, or possibly under "membrane" or "membrane protein" and things like that. N-neuraminic acid is used within the N- and O-glycosylation pathways and most membrane proteins are also glycosylated to some degree.