Perhaps you should try some spelling variations:
thanh vai » thanh hai, thanh van, thanh tai
van thanh » ban thanh, van tuan
ve triet » va trien, su triet
tang xa » trang xa, tang ma, lang xa
hieu va » hieu qua
sach ky » sach y, sach ty, sach kem
cam luu » tam luu
luu van » cuu van, luan van, luu hanh
sac ky » cac ky, sai ky
vai ve » va ve, dai ve, vai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc ((sach ky) or (sac ky)) tang xa hoi. ((hieu va) OR (lieu va)) cam luu van thanh vai ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc ((sach ky) OR (sac ky)) tang xa hoi. ((hieu va) OR (lieu va)) cam luu van thanh vai ve triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc ((sach ky) or (sac ky)) tang xa hoi. ((hieu va) OR (lieu va)) cam luu van thanh vai ve triet".
• Adding a wildcard symbol may retrieve word variants: thuoc ((sach ky) or (sac ky)) tang xa hoi. ((hieu va) OR (lieu va)) cam luu van thanh vai ve triet*.