1. Alexiewicz, A.: Linear functionals on Denjoy-integrable functions. Colloquium Mathematicum 1, 289–293 (1948)
2. Aulbach, B., Siegmund, S.: A spectral theory for nonautonomous difference equations. In: Elaydi, S., Lopez-Fenner, J., Ladas, G., Pinto, M. (eds.) Proc. 5th Intern. Conf. of Difference Eqns. and Appl., pp. 45–55. Taylor & Francis (2000)
3. Aulbach, B., Siegmund, S.: The dichotomy spectrum for noninvertible systems of linear difference equations. J. Differ. Equ. Appl. 7(6), 895–913 (2001)
4. Bartle, R.G.: A Modern Theory of Integration, volume 32 of Graduate Studies in Mathematics. Amer. Math. Soc., Providence, RI, USA (2001)
5. Chew, T.S., Flordeliza, F.: On $$x^{\prime }=f(t, x)$$ and Henstock–Kurzweil integrals. Differ. Integral Equ. 4(4), 861–868 (1991)