The two-period cross-over clinical trialAuthors' commentaryHills, MArmitage, PAuthor information158A North Hill, London N6 4RH, UK. E-mail: [email protected]22 Reading Road, Wallingford, Oxon OX10 9DP, UK. E-mail: [email protected]M Hills, P Armitage. Br J Clin Pharmacol 1979; 8 (1) Jul: 7-20.British Journal of Clinical Pharmacology 58(7):p S717-718, December 2004.Copyright © 2004 John Wiley & Sons, Ltd