Perhaps you should try some spelling variations:
thanh vai » thanh hai, thanh van, thanh tai
van thanh » ban thanh, van tuan
va trien » va truyen, va thiet, va tuyen
tang xa » trang xa, tang ma, lang xa
sach ky » sach y, sach ty, sach kem
luu van » cuu van, luan van, luu hanh
sac ky » cac ky, sai ky
va cao » va cac, va co, va dao
vai va » mai va, dai va, hai va
va cam » va cham, va cac, va cai

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 cam) OR (va cao)) luu van thanh vai va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc ((sach ky) OR (sac ky)) tang xa hoi. hieu ((va cam) OR (va cao)) luu van thanh vai va trien*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc ((sach ky) or (sac ky)) tang xa hoi. hieu ((va cam) OR (va cao)) luu van thanh vai va trien*".