Searching for c# code to convert from UTM to WGS1984 (and back)

I'm looking for code in c# that converts coordinates from UTM to WGS1984 (and preferably backwards as well). I need to convert coordinates from only one zone (36N).

I've found this and this, but they throw me 150-200 meters from the real point (The allowed diversion I'm aiming for is 5 meters tops).

EDIT: Found this as well, but did not have an opportunity to check this for accuracy.

thanks in advance.

EDIT: Found this as well, but did not have an opportunity to check this for accuracy.