Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
su triet » su viet, su tien, ve triet
thanh va » thanh van, hanh va, thanh ha
nam thuc » nam thuoc, am thuc, nam thu
cam tuc » cam xuc, cam tu, dam thuc
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
tang ma » mang may, tang van

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky ((nang x) or (tang ma)) hoi. hieu ve ((cam tuc) OR (nam thuc)) ban thanh va su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky ((nang x) OR (tang ma)) hoi. hieu ve ((cam tuc) OR (nam thuc)) ban thanh va su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky ((nang x) or (tang ma)) hoi. hieu ve ((cam tuc) OR (nam thuc)) ban thanh va su triet".
• Adding a wildcard symbol may retrieve word variants: vu sach ky ((nang x) or (tang ma)) hoi. hieu ve ((cam tuc) OR (nam thuc)) ban thanh va su triet*.