Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
van hanh » van thanh, ban hanh, van anh
tru nang » tra nang, tri nang, truc nano
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
cac vuc » cac vung, cac cuoc, cac quoc
hanh di » hanh vi, hanh de, hang di
cua cau » cua cac, cua chu, cua cay
hieu ve » hieu va, hieu van
cho hoc » co hoc, khoa hoc
tu nang » tu nong, tu nano, tu lang
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ((tu nang) OR (tru nang)) cho hoc. hieu ve ((cac vuc) or (cac nuoc)) van hanh di cua cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ((tu nang) OR (tru nang)) cho hoc. hieu ve ((cac vuc) OR (cac nuoc)) van hanh di cua cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ((tu nang) OR (tru nang)) cho hoc. hieu ve ((cac vuc) or (cac nuoc)) van hanh di cua cau*".