Namba H, Iyo M, Fukushi K, Shinotoh H, Nagatsuka S, Suhara T, Sudo Y, Suzuki K, Irie T. Human cerebral acetylcholinesterase activity measured with positron emission tomography: procedure, normal values and effect of age. Eur J Nucl Med. 1999 Feb;26(2):135-43. PubMed Abstract