Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hang doi » hang di, hang loi, huong doi
duc ban » duc tan, dua ban, duc man
doi cua » dai cua, hoi cua
duc van » duc va, duc tan, duc manh
cua tre » cua te, cuu tre, cua triet
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) OR (duc van)) hang doi 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) OR (duc van)) hang doi 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) OR (duc van)) hang doi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky nang o hoc. lieu va nam ((duc ban) OR (duc van)) hang doi cua tre*.