Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach thu » sach thue, sach thieu, sach tham
thu bang » thu ban, thu hang, chu bang
van hanh » van thanh, ban hanh, van anh
hanh lai » hanh lam, hanh tai, thanh lap
bang xa » lang xa, bang va, mang xa
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac nuoc
cac dac » cac dan, cac dai, cac bac
lai cua » dai cua, hai cua, lai chau
cua tre » cua te, cuu tre, cua triet

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 thu bang xa hoi. hieu va ((cac duc) OR (cac dac)) van hanh lai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach thu bang xa hoi. hieu va ((cac duc) OR (cac dac)) van hanh lai cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach thu bang xa hoi. hieu va ((cac duc) OR (cac dac)) van hanh lai cua tre*.