Perhaps you should try some spelling variations:
danh va » doanh va, hanh va, anh va
va danh » va dinh, va dan, va hanh
sach ky » sac ky, sach ty, sach kem
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
so viet » hoc viet
ma hoi » mai hoi, xa hoi, ma hoa
va dam » van dam, va dao, va dau
dam tu » nam tu, cam tu, tam tu

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 ky) OR (sach y)) nang ma hoi. hieu va dam tu va danh va ((su viet) or (so viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sach y)) nang ma hoi. hieu va dam tu va danh va ((su viet) OR (so viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ky) OR (sach y)) nang ma hoi. hieu va dam tu va danh va ((su viet) or (so viet))".
• Adding a wildcard symbol may retrieve word variants: te ((sach ky) OR (sach y)) nang ma hoi. hieu va dam tu va danh va ((su viet) or (so viet))*.