Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
manh hai » lanh hai, minh hai, thanh hai
ban manh » ban hanh, van manh, ban mach
nganh ma » nganh mac, nganh hoa, nganh y
hieu va » lieu va, hieu qua
hai cua » thai cua, dai cua, hoi cua
duc ban » duc tan, duc van, dua ban
cac duc » cac du, cao duc, cac dac
hieu ve » hieu van
sach ky » sac ky, sach y, sach ty
anh xay » manh xay, anh hay, nganh xay
cua tre » cua te, cuu tre, cua triet

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 ((anh xay) or (nganh ma)) hoi. ((hieu ve) or (hieu va)) cac duc ban manh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((anh xay) OR (nganh ma)) hoi. ((hieu ve) OR (hieu va)) cac duc ban manh hai cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((anh xay) or (nganh ma)) hoi. ((hieu ve) or (hieu va)) cac duc ban manh hai cua tre*.