Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
hanh lai » hanh lam, hanh tai, thanh lap
van hanh » van thanh, ban hanh, van anh
lai cua » dai cua, hai cua, lai chau
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
hieu va » lieu va, hieu qua
bang va » hang va, ban va, trang va
cua tre » cua te, cuu tre, cua triet
bang xa » lang xa, mang xa, ang xa

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) or (hoc sach)) thu ((bang xa) OR (bang va)) hoi. hieu va cac duc van hanh lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) thu ((bang xa) OR (bang va)) hoi. hieu va cac duc van hanh lai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) thu ((bang xa) OR (bang va)) hoi. hieu va cac duc van hanh lai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) thu ((bang xa) OR (bang va)) hoi. hieu va cac duc van hanh lai cua tre*.