Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dua tren » dung tren
nang ro » nang co, nang ho, nang ra
van cac » van hac, van cau, van bac
cuu tre » cua tre, cau tren, cau treo
tang ho » tang cho, tung ho, tang ha
sac ky » cac ky, sai ky
cac tu » cac thu, cach tu, cac du
tu sac » tu sach, tu cac, tu san
va do » va dao, va doc, va co
do vi » don vi, doc vi, do voi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky ((tang ho) or (nang ro)) hoi. hieu van cac tu va do vi ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky ((tang ho) OR (nang ro)) hoi. hieu van cac tu va do vi ((dua tren) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: tu sac ky ((tang ho) or (nang ro)) hoi. hieu van cac tu va do vi ((dua tren) or (cuu tre))*.