Perhaps you should try some spelling variations:
dua tren » dung tren
cac thuc » cach thuc, cac thu, can thuc
tu sach » thu sach, su sach, te sach
hang vi » hang va, hanh vi, hang di
va hang » van hang, va nang, va lang
thuc va » thuc vat, thuc dan, thuc day
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau tren, cau treo
hieu ve » hieu va, hieu van
lang ha » long ha
lang xa » dang xay, lang van
ve cac » va cac, vien cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky ((lang xa) or (lang ha)) hoi. hieu ve cac thuc va hang vi ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((lang xa) OR (lang ha)) hoi. hieu ve cac thuc va hang vi ((dua tren) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((lang xa) or (lang ha)) hoi. hieu ve cac thuc va hang vi ((dua tren) or (cuu tre))*.