On Direct and Inverse Proportionality. - Markku Halmetoja; Pentti Haukkanen; Teuvo Laurinolli; Jorma K. Merikoski; Timo Tossavainen; Ari Virtanen (Am. Math. Mon., 2007)

Asymptotics for numbers of line segments and lines in a square grid - Pentti Haukkanen; Jorma K. Merikoski (CoRR, 2011)

Some formulas for numbers of line segments and lines in a rectangular grid. - Pentti Haukkanen; Jorma K. Merikoski (Ars Comb., 2012)

Asymptotics of the number of threshold functions on a two-dimensional rectangular grid. - Pentti Haukkanen; Jorma K. Merikoski (Discret. Appl. Math., 2013)

Perpendicularity in an Abelian Group. - Pentti Haukkanen; Mika Mattila; Jorma K. Merikoski; Timo Tossavainen (Int. J. Math. Math. Sci., 2013)

On Arithmetic Partial Differential Equations. - Pentti Haukkanen; Jorma K. Merikoski; Timo Tossavainen (J. Integer Seq., 2016)

The Arithmetic Jacobian Matrix and Determinant. - Pentti Haukkanen; Jorma K. Merikoski; Mika Mattila; Timo Tossavainen (J. Integer Seq., 2017)

Arithmetic Subderivatives: Discontinuity and Continuity. - Pentti Haukkanen; Jorma K. Merikoski; Timo Tossavainen (J. Integer Seq., 2019)