1. Graphical display of means;Andrews;Am. Statistician,1980
2. Tramadol and pentazocine-a clinical double- blind cross-over comparison;Arend;Arzneim.-Forsch./Drug Res.,1978
3. Experimental Designs;Cochran,1957
4. Effects of tramadol on noradrenaline release from rat brain cortex slices;Driessen;Naunyn-Schmiedeberg's Arch. Pharmacol.,1989
5. Statistical Method in Biological Assay;Finney,1964