Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thu sach » tu sach, thuat sach, thuoc sach
cau tren » cu tren, dau tren, ca tren
thanh de » hanh de, thanh ve, thanh do
ve triet » va trien, su triet
hieu ve » hieu van
sach ty » sach y, sach tu, sach thu
duc ban » duc tan, duc van, dua ban
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
hieu va » lieu va, hieu qua
ma hoi » mai hoi, xa hoi, ma hoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty nang ma hoi. ((hieu ve) OR (hieu va)) pham duc ban thanh de ((cau tren) OR (ve triet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty nang ma hoi. ((hieu ve) OR (hieu va)) pham duc ban thanh de ((cau tren) or (ve triet))~".
• Adding a wildcard symbol may retrieve word variants: thu sach ty nang ma hoi. ((hieu ve) OR (hieu va)) pham duc ban thanh de ((cau tren) or (ve triet))*.