Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thu sach » tu sach, thuat sach, thu hoach
hanh hai » thanh hai, nhanh hai, hang hai
ban hanh » ban hang
hieu van » thien van, lieu va, hieu ve
dau tren » dau tien, dat tren, dau tieng
ly nang » ky nang, ly hang, ly vang
hieu va » lieu va, hieu qua
cam duc » cam xuc, cao duc, pham duc
duc ban » duc tan, duc van, dua ban
hai dau » han dau, hai dan, hai hau
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (thuoc sach)) ly nang x hoi. ((hieu van) or (hieu va)) cam duc ban hanh hai dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuoc sach)) ly nang x hoi. ((hieu van) OR (hieu va)) cam duc ban hanh hai dau tren.
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuoc sach)) ly nang x hoi. ((hieu van) or (hieu va)) cam duc ban hanh hai dau tren*.