Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thu nang » thi nang, thu hang, thu bang
hanh de » hanh ve, hanh kem
duc ban » duc tan, duc van, dua ban
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, nang ma
va cam » va cham, va cac, va cao
de cua » le cua, te cua, dieu cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) thu nang xa hoi. hieu va cam ((cua ban) or (duc ban)) hanh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) thu nang xa hoi. hieu va cam ((cua ban) OR (duc ban)) hanh de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) thu nang xa hoi. hieu va cam ((cua ban) or (duc ban)) hanh de cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) thu nang xa hoi. hieu va cam ((cua ban) or (duc ban)) hanh de cua tre*.