Perhaps you should try some spelling variations:
sach duoc » sach nuoc, sach dao, sach dung
duoc nang » duoc nhung, dun nang, dung nang
van hanh » van thanh, ban hanh, van anh
xuc van » duc van, luc van, vuc van
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
va cam » va cham, va cac, va cai
ma hoi » mai hoi, xa hoi, ma hoa
va cao » va cac, va co, va dao
ki ve » gi ve, vi ve
ke ve » ke va, ke he, de ve

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 duoc nang ma hoi. hieu ((va cam) OR (va cao)) xuc van hanh ((ki ve) or (ke ve)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach duoc nang ma hoi. hieu ((va cam) OR (va cao)) xuc van hanh ((ki ve) OR (ke ve)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach duoc nang ma hoi. hieu ((va cam) OR (va cao)) xuc van hanh ((ki ve) or (ke ve)) triet".
• Adding a wildcard symbol may retrieve word variants: tu sach duoc nang ma hoi. hieu ((va cam) OR (va cao)) xuc van hanh ((ki ve) or (ke ve)) triet*.