Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van ban
te sach » toc sach
van anh » van thanh, tuan anh, van minh
cac vuc » cac nuoc, cac vung, cac cuoc
hieu va » lieu va, hieu qua
cho hoc » co hoc, khoa hoc
ty hang » ly hang, ty xang, thi hang
ty tang » tay tang, ty xang, ky tang
cua cau » cua cac, cua chu, cua cay
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: te sach ((ty tang) or (ty hang)) cho hoc. hieu va cac vuc ((van hanh) OR (van anh)) vi cua cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ty tang) OR (ty hang)) cho hoc. hieu va cac vuc ((van hanh) OR (van anh)) vi cua cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ty tang) or (ty hang)) cho hoc. hieu va cac vuc ((van hanh) OR (van anh)) vi cua cau*".