Perhaps you should try some spelling variations:
nang hoat » nang hoa, trang hoat, hang hoa
canh tac » canh tay, canh giac, cong tac
tac vang » cac van, tac dung, tac dong
vang hoa » vang khoa, van hoa, hang hoa
hien nam » phien nam, hien nay, mien nam
vien nam » viet nam, vien dai, van nam
nang hoc » nang doc, nang luc, dong hoc

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( canh tac vang hoa ((hien nam) or (vien nam)) ) or ( doanh tai ((nang hoat) or (nang hoc)) ((hien nam) or (vien nam)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( canh tac vang hoa ((hien nam) OR (vien nam)) ) OR ( doanh tai ((nang hoat) OR (nang hoc)) ((hien nam) OR (vien nam)) )).
• Adding a wildcard symbol may retrieve word variants: (( canh tac vang hoa ((hien nam) or (vien nam)) ) or ( doanh tai ((nang hoat) or (nang hoc)) ((hien nam) or (vien nam)) ))*.