Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
toc sach » hoc sach, doc sach, nuoc sach
hieu van » hieu va, thien van, lieu va
hanh hai » thanh hai, nhanh hai, hang hai
van hanh » van thanh, ban hanh, van anh
van pham » san pham, van phan, van phat
hai cua » thai cua, dai cua, hoi cua
duc van » duc va, duc tan, duc manh
mai hoi » mai khoi, dai hoi, lai hoi
cua tu » cua tuc, cua su, cua cu
ma hoi » xa hoi, ma hoa, me hoi
v nang » va nang, vu nang, van nang

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) or (thuoc sach)) v nang ((ma hoi) or (mai hoi)). hieu van pham duc van hanh hai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thuoc sach)) v nang ((ma hoi) OR (mai hoi)). hieu van pham duc van hanh hai cua tu.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (thuoc sach)) v nang ((ma hoi) or (mai hoi)). hieu van pham duc van hanh hai cua tu*.