Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
dua tren » dung tren
bo sach » co sach, hoc sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
soc van » hoc van, oc van, sac van
cuu tre » cua tre, cau tren, cau treo

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

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