Perhaps you should try some spelling variations:
hanh dao » lanh dao, thanh dat, thanh dam
ban hanh » ban hang
may thoi » gay thoi, may thi, tay thoi
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
tuc ban » thuc ban, truc ban, tu ban
cac tuc » cac toc, cac tu, cac tac
hieu va » lieu va, hieu qua
may hoi » tay hoi, mai hoi, may hmi
ky mang » ky nang, ke mang, ky dang
so viet » hoc viet

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky mang ((may hoi) or (may thoi)). hieu va cac tuc ban hanh dao ((su viet) OR (so viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky mang ((may hoi) OR (may thoi)). hieu va cac tuc ban hanh dao ((su viet) OR (so viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky mang ((may hoi) or (may thoi)). hieu va cac tuc ban hanh dao ((su viet) OR (so viet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky mang ((may hoi) or (may thoi)). hieu va cac tuc ban hanh dao ((su viet) OR (so viet))*.