Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
van bac » van ban, van bao, van hac
bac hoc » bai hoc, bac ho
va hanh » van hanh, va thanh, va danh
cua tre » cuu tre, cua triet, dua tren
tu sac » tu sach, tu san, tu bac
cua te » cua tu

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) or (tu cac)) ky lang xa hoi. hieu van bac hoc va hanh vi ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sac) OR (tu cac)) ky lang xa hoi. hieu van bac hoc va hanh vi ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sac) or (tu cac)) ky lang xa hoi. hieu van bac hoc va hanh vi ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: ((tu sac) or (tu cac)) ky lang xa hoi. hieu van bac hoc va hanh vi ((cua tre) OR (cua te))*.