Perhaps you should try some spelling variations:
cach thien » cach thiet, sach thieu, cai thien
sach tien » sach tren, sach thieu
hieu van » hieu va, thien van, hieu ve
nang xa » nang x, lang xa, nang ma
phap tu » phan tu, pham tu
va dinh » van dinh, va kinh, va tinh
cu tren » tu tren, dua tren
van cu » van cau, van chu, van cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((cach thien) or (sach tien)) nang xa hoi. ((hieu van) or (lieu va)) phap tu va dinh van cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((cach thien) OR (sach tien)) nang xa hoi. ((hieu van) OR (lieu va)) phap tu va dinh van cu tren.
• Adding a wildcard symbol may retrieve word variants: tu ((cach thien) or (sach tien)) nang xa hoi. ((hieu van) or (lieu va)) phap tu va dinh van cu tren*.