Perhaps you should try some spelling variations:
thanh thai » thanh hai, thanh tai, nhanh thai
ban thanh » ban hanh, ban hang
cau tren » cu tren, dau tren, ca tren
thai cau » thai cao, toan cau, thai van
hieu van » hieu va, thien van, lieu va
cuc ban » cua ban, cac ban, cuu ban
cac cuc » cac cuoc, cac cua, cac nuoc
van cac » van hac, van cau, van bac
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
so ha » so hoa, so va
o hoc » co hoc, mo hoc, so hoc
o lai » o lao

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang ((o hoc) or (((so ha) or (o lai)))). hieu van cac cuc ban thanh thai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoc) OR (((so ha) OR (o lai)))). hieu van cac cuc ban thanh thai cau tren.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoc) or (((so ha) or (o lai)))). hieu van cac cuc ban thanh thai cau tren*.