Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
te sach » toc sach
hieu va » lieu va, hieu qua
cam duc » cam xuc, cao duc, pham duc
dan sai » danh sai, doan sai, dan tai
va cam » va cham, va cac, va cao
va dan » ca dan, va dao, va dau
cua su » qua su

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((7 tang) OR (6 tang)) xa hoi. hieu va cam duc va dan sai ((cua viet) or (cua su))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((7 tang) OR (6 tang)) xa hoi. hieu va cam duc va dan sai ((cua viet) OR (cua su)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((7 tang) OR (6 tang)) xa hoi. hieu va cam duc va dan sai ((cua viet) or (cua su))".
• Adding a wildcard symbol may retrieve word variants: te sach ((7 tang) OR (6 tang)) xa hoi. hieu va cam duc va dan sai ((cua viet) or (cua su))*.