Perhaps you should try some spelling variations:
sach thien » sach thieu, sach tien, cach thien
thien nang » thien bang, thien dang, trien nang
dinh vai » dinh van, dinh vi, dinh va
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
hieu ve » hieu van
hieu va » lieu va, hieu qua
phap tu » phan tu, pham tu
va dinh » van dinh, va kinh, va tinh
cu tren » tu tren, dua tren
vai cu » vai cua, van cu

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 thien nang xa hoi. ((hieu ve) or (hieu va)) phap tu va dinh vai cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thien nang xa hoi. ((hieu ve) OR (hieu va)) phap tu va dinh vai cu tren.
• Adding a wildcard symbol may retrieve word variants: tu sach thien nang xa hoi. ((hieu ve) or (hieu va)) phap tu va dinh vai cu tren*.