Dab tsi yog cov khoom ntawm kev ua cov hlau stamping? Coob leej tsis paub, vim hais tias cov khoom lag luam xws li, yog li muaj ntau yam kev lag luam steeling, yog suav nrog kev lag luam cov khoom lag luam steeling ua teb .
Hauv kev tsim kho cov khoom lag luam zoo nkauj, muaj qee qhov kev lag luam stamping uas tau tsim kho cov khoom lag luam hlau zoo thiab tsim cov khoom lag luam zoo nkauj ntawm kev lag luam .} ntawm chav kawm, nws lub sij hawm nqi sib txawv .
