Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu va » hieu qua
cac loc » cac lop, cac toc, cac hoc
doan vi » doan va, don vi, doan thi
cuu tre » cua tre, cau tren, cau treo
loc va » hoc va, luc va
dan vi » don vi, dan va, gan vi

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang xa hoi. ((hieu va) or (lieu va)) cac loc va ((dan vi) OR (doan vi)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang xa hoi. ((hieu va) OR (lieu va)) cac loc va ((dan vi) OR (doan vi)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang xa hoi. ((hieu va) or (lieu va)) cac loc va ((dan vi) OR (doan vi)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang xa hoi. ((hieu va) or (lieu va)) cac loc va ((dan vi) OR (doan vi)) cuu tre*.