On certain trigonometric sums in several variables. P. Haukkanen; R. Sivaramakrishnan — 1994 Collectanea Mathematica
Rational arithmetical functions of order (2,1) with respect to regular convolutions. Haukkanen, P. — 1999 Portugaliae Mathematica
A generalization of Menon's identity with respect to a set of polynomials. Haukkanen, P.; Wang, J. — 1996 Portugaliae Mathematica
On an analogue of completely multiplicative functions. Haukkanen, P.; Ruokonen, P. — 1997 Portugaliae Mathematica