Perhaps you should try some spelling variations:
thien nang » thien bang, thien dang, thien cong
trien nang » trien nong, trien mang, trien quang
dinh vai » dinh van, dinh vi, dinh va
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
va dinh » van dinh, va kinh, va tinh
phap tu » phan tu, pham tu
cu tren » tu tren, dua tren
hieu ve » hieu van
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) OR (trien 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) OR (trien nang)) xa hoi. ((hieu ve) OR (hieu va)) phap tu va dinh vai cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((thien nang) OR (trien 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) OR (trien nang)) xa hoi. ((hieu ve) or (hieu va)) phap tu va dinh vai cu tren*.