1. Cai, T.: On 2-Niven numbers and 3-Niven numbers. Fibonacci Q. 34, 118–120 (1996)
2. Cooper, C., Kennedy, R.E.: On consecutive Niven numbers. Fibonacci Q. 31, 146–151 (1993)
3. De Koninck, J.M., Doyon, N.: Large and small gaps between consecutive Niven numbers. J. Integer Seq. 6 (2003). Article 03.2.5
4. De Koninck, J.M., Doyon, N., Kátai, I.: On the counting function for the Niven numbers. Acta Arith. 106, 265–275 (2003)
5. Grundman, H.G.: Sequences of consecutive n-Niven numbers. Fibonacci Q. 32, 174–175 (1994)