Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ban hanh » ban hang
duc ban » duc tan, duc van, dua ban
hoi cua » hoi chuc
doi cua » dai cua
nam duc » nam duoc, pham duc, nam thuc
nang o » nang co, nang ho, nang ro
va nam » van nam, ha nam, va nay
o hoc » co hoc, mo hoc, so hoc

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)) ky nang o hoc. lieu va nam duc ban hanh ((doi cua) OR (hoi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky nang o hoc. lieu va nam duc ban hanh ((doi cua) OR (hoi cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ky nang o hoc. lieu va nam duc ban hanh ((doi cua) OR (hoi cua)) tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky nang o hoc. lieu va nam duc ban hanh ((doi cua) OR (hoi cua)) tre*.