1. Atchley, W. R., C. T. Gaskins and D. Anderson. 1976. Statistical properties of ratios. I. Empirical results. Syst. Zool., 25: 137–148.
2. Azuma, M. 1973a. Studies on the variability of the landlocked Ayu-fish,Plecoglossus altivelis T. et S., in Lake Biwa. III. On the segregation of population and the variations in each population. Japan. J. Ecol., 23: 126–139. (In Japanese with English abstract.)
3. Azuma, M. 1973b. Studies on the variability of the landlocked Ayu-fish,Plecoglossus altivelis T. et S., in Lake Biwa. IV. Considerations on the grouping and features of variability. Japan. J. Ecol., 23: 255–265. (In Japanese with English abstract.)
4. Azuma, M. 1981. On the origin of Koayu, a land-locked form of amphidromous Ayu-fish,Plecoglossus altivelis. Verh. Internat. Verein. Limnol., 21: 1291–1296.
5. Clyaton, J. W. 1981. The stock concept and the uncoupling of organismal and molecular evolution. Can. J. Fish. Aquat. Sci., 38: 1515–1522.