The original calculations were done by an astronomer called Frank Bash: you could Google him if interested.
My primary reference for Bash's work is paper-based: The Guide to the Galaxy (Cambridge University Press, 1994), by two astronomers called Nigel Henbest and Heather Couper. Fortunately, the relevant section describing the Sun's orbit is quoted on-line here at Stanford University's Solar Center.
A year after Henbest & Couper's book was published, a paper appeared in the Astronomical Journal providing a revised estimate for the Sun's distance from the galactic plane of 20.5 +/- 3.5 parsecs: in round numbers, that's around 70 light years. See The Sun's Distance Above the Galactic Plane, by Roberta Humphreys & Jeffrey Larsen.

However, from Astrophysics and Space Science in 2003, I now find The Sun's Distance From the Galactic Plane, by RL Branham, which claims tighter error bars and places us ~110 light years from the galactic plane. The estimates seem to keep on going up as the measurements are refined.

Grant Hutchison