Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
chat luc » chat xuc, chat lua, nhan luc
hieu va » lieu va, hieu qua
hanh le » thanh le, hanh ve, hanh de
luc van » luoc van, luu van, duc van
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
hieu ve » hieu van
mai hoi » mai khoi, dai hoi, lai hoi
le cua » ly cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky nang ((xa hoi) or (mai hoi)). ((hieu ve) OR (hieu va)) chat luc van hanh le cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang ((xa hoi) OR (mai hoi)). ((hieu ve) OR (hieu va)) chat luc van hanh le cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang ((xa hoi) or (mai hoi)). ((hieu ve) OR (hieu va)) chat luc van hanh le cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang ((xa hoi) or (mai hoi)). ((hieu ve) OR (hieu va)) chat luc van hanh le cua tre*.