1. Apparently, W.J. Paul [Proc. Int. Conf. Fund. Comput. Theory, L. Budach (Ed.), 1979, pp. 325-334]
2. R.V. Freivalds [‘On the running time of deterministic and nondeterministic Turing machines,’ Latv. Mat. Ezhegodnik, 23 (1979) 158–165 (in Russian)]
3. W.J. Paul, J. Seiferas, and J. Simon, [J. Comput. System Sci., 23:2(1981), 108–126].
4. W.J. Paul, which contains Section 6.1.1, page 380, was not widely circulated.
5. S.O. Aanderaa [pp.75-96 in: Complexity of Computation, R. Karp (Ed.), Amer. Math. Soc, 1974].