Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, hieu ve
nang xa » nang x, lang xa, nang ma
dau hai » dai hai, dau ha, cau hai
ca viet » va viet, hoa viet, san viet
co viet » so viet, o viet, hoc viet
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
va dau » va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach v nang xa hoi. ((hieu van) OR (lieu va)) giao duc va dau hai ((ca viet) or (co viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach v nang xa hoi. ((hieu van) OR (lieu va)) giao duc va dau hai ((ca viet) OR (co viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach v nang xa hoi. ((hieu van) OR (lieu va)) giao duc va dau hai ((ca viet) or (co viet))".
• Adding a wildcard symbol may retrieve word variants: thu sach v nang xa hoi. ((hieu van) OR (lieu va)) giao duc va dau hai ((ca viet) or (co viet))*.