Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
nano cho » nang cho, nano cuo, nang chon
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
cac vuc » cac vung, cac cuoc, cac quoc
hanh va » hang va, hanh vi
cua chu » sua chua
hieu ve » hieu va, hieu van
cho hoc » co hoc, khoa hoc
tu nano » truc nano
va cua » va chua, via cua, ca cua

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) tu nano cho hoc. hieu ve ((cac vuc) OR (cac nuoc)) van hanh va cua chu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) tu nano cho hoc. hieu ve ((cac vuc) or (cac nuoc)) van hanh va cua chu~".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) tu nano cho hoc. hieu ve ((cac vuc) or (cac nuoc)) van hanh va cua chu*.