Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
cac tac » cac bac, cac dac, cac tai
cua tre » cuu tre, cua triet, dua tren
lang xa » lang ha, dang xay, lang van
cac toc » cac toi, cac nuoc, cac thoi
va hanh » van hanh, va thanh, va danh
cua te » cua tu
sach o » sach lo, sac o, sach y
o lang » hoa lang, hoi lang

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach o lang xa hoi. hieu van ((cac toc) or (cac tac)) va hanh vi ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach o lang xa hoi. hieu van ((cac toc) OR (cac tac)) va hanh vi ((cua tre) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: su sach o lang xa hoi. hieu van ((cac toc) or (cac tac)) va hanh vi ((cua tre) or (cua te))*.