Key points are not available for this paper at this time.
Submillimeter measurements of the effective masses yield values of m_^*=0. 299m₀ and m_^*=0. 234m₀ for the electron. The density-of-states effective mass is 0. 275m₀. These direct measurements resolve the long-standing conflict among variety of reports which have ranged from 0. 1 to 0. 4m₀.
Button et al. (Wed,) studied this question.