Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
cac vuc » cac vung, cac cuoc, cac quoc
hieu ve » hieu va, hieu van
cho hoc » co hoc, khoa hoc
tu nong » tu dong, tu cong, tu tong
tu nang » tru nang, tu nano, tu lang
cua chu » sua chua
vi cua » vai cua, di cua

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 ((tu nang) or (tu nong)) cho hoc. hieu ve ((cac vuc) OR (cac nuoc)) van hanh vi cua chu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((tu nang) OR (tu nong)) cho hoc. hieu ve ((cac vuc) OR (cac nuoc)) van hanh vi cua chu*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((tu nang) or (tu nong)) cho hoc. hieu ve ((cac vuc) OR (cac nuoc)) van hanh vi cua chu*".