My wife is a cook - she says recipes using weights are more consistent than volume no matter your units preference but I think you are missing a connection... if you are using weights (grams) you need a scale... period - none of those books will tell you a universal gram to teaspoon conversion and there is not metric equivalent to a teaspoon... but if you do find yourself with a cookbook mentioning weight/grams just plop it in a container on your scale (hell that container can be a half cup measuring cup) and move along.