Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » thien van, hieu ve
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
nang xa » nang x, lang xa, nang ma
hieu va » hieu qua
cac loc » cac lop, cac toc, cac hoc
va doan » va doanh, van doan, va dan
doan vi » doan va, don vi, doan thi
cua tre » cua te, cuu tre, cua triet
loc va » hoc va, luc va
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: thu sach ty nang xa hoi. ((((hieu van) or (hieu va))) or (lieu va)) cac loc va doan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty nang xa hoi. ((((hieu van) OR (hieu va))) OR (lieu va)) cac loc va doan vi cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach ty nang xa hoi. ((((hieu van) or (hieu va))) or (lieu va)) cac loc va doan vi cua tre*.