Perhaps you should try some spelling variations:
te sach » toc sach
va hanh » van hanh, va thanh, va danh
cau luc » cau truc, cau phuc
hieu va » lieu va, hieu qua
tay hoi » tay ho, tao hoi, tay thai
xay hoi » xa hoi, cay phoi, gay thoi
ky dang » ky nang, ky danh
cuu tre » cua tre, cau tren, cau treo
va cau » van cau, va cac, va dau
luc va » duc va, tuc va, loc va
vi cuu » vi luu, vinh cuu

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) or (thu hoach)) ky dang ((xay hoi) OR (tay hoi)). hieu va cau luc va hanh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (thu hoach)) ky dang ((xay hoi) OR (tay hoi)). hieu va cau luc va hanh vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (thu hoach)) ky dang ((xay hoi) OR (tay hoi)). hieu va cau luc va hanh vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (thu hoach)) ky dang ((xay hoi) OR (tay hoi)). hieu va cau luc va hanh vi cuu tre*.