1. Enzymatic barriers to peptide and protein absorption;Lee;CRC Crit. Rev. Ther. Drug Carrier Syst.,1988
2. Advanced delivery systems for peptides and proteins — pharmaceutical considerations;Davis,1986
3. The oral bioavailability of peptides and related drugs;Humphrey,1986
4. Peptides and related drugs: a review of their absorption, metabolism and excretion;Ringrose;Drug Met. Rev.,1986
5. Penetration and enzymatic barriers to peptide absorption;Lee;Adv. Drug Del. Rev.,1990