Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
tuan hoc » toan hoc, luan hoc, than hoc
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
luu tre » luu tru, cuu tre, luy tre
te sac » te sach, te san
te cac » tu cac, ve cac, te cao
vi luu » vi lua

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

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