Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam tu
doanh va » doan va, doanh cua, hanh va
ve triet » va trien, su triet
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
ma hoi » mai hoi, xa hoi, ma hoa

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

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