Ua ntej xyoo 1970, kev lag luam hluav taws xob tau siv cov khoom siv hluav taws xob los ua cov dej khov thiab tiv thaiv tshav kub.Tom qab ntawd mus rau thaum ntxov 1980s, tom qab kev tshawb fawb thiab kev hloov kho, chav cua sov tracing tau hloov los ntawm hluav taws xob cua sov tracing.Cov thev naus laus zis tau raug txhim kho tsis tu ncua hauv kev xyaum, thiab nws tau ua ...
Nyeem ntxiv