Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach lo » sach dao, sach doi, sach hoi
lo nang » ho nang, ly nang, loai nang
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac dac
va doan » va doanh, van doan, va dan
doan vi » doan va, don vi, doan thi
cua tre » cua te, cuu tre, cua triet
luy tre » luyen tre
ve cac » va cac, vien cac
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: toc sach lo nang x hoi. hieu ve cac duc va doan vi ((cua tre) or (luy tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach lo nang x hoi. hieu ve cac duc va doan vi ((cua tre) OR (luy tre)).
• Adding a wildcard symbol may retrieve word variants: toc sach lo nang x hoi. hieu ve cac duc va doan vi ((cua tre) or (luy tre))*.