Key points are not available for this paper at this time.
H. J. Malmquist, S. S. Snorrason, , B. Jonsson, O. T. Sandlund, P. M. Jonasson, Diet Differentiation in Polymorphic Arctic Charr in Thingvallavatn, Iceland, Journal of Animal Ecology, Vol. 61, No. 1 (Feb., 1992), pp. 21-35
Malmquist et al. (Sat,) studied this question.