Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thu sach » tu sach, thuat sach, thu hoach
hieu van » hieu va, thien van, lieu va
tang ma » mang may, tang van
van cam » van nam, van lam, van cau
cam duc » cam xuc, cao duc, pham duc
va doan » va doanh, van doan, va dan
doan vi » doan va, don vi, doan thi
cua tuc » cua duc, cua tu, cua thuoc
v tang » 6 tang, 7 tang, 5 tang
cua su » qua su

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)) v tang ma hoa. hieu van cam duc va doan vi ((cua tuc) or (cua su))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuoc sach)) v tang ma hoa. hieu van cam duc va doan vi ((cua tuc) OR (cua su)).
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuoc sach)) v tang ma hoa. hieu van cam duc va doan vi ((cua tuc) or (cua su))*.