Perhaps you should try some spelling variations:
thieu khang » chieu khong, thieu quang
khang xa » khang a, hang ca, lang xa
hieu van » thien van, lieu va, hieu ve
kinh vai » kinh va, kinh van, sinh vat
kinh hai » tinh hai, minh hai, dinh hai
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
phap tu » phan tu, pham tu
cu tren » tu tren, dua tren

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 thieu khang xa hoi. ((hieu van) or (hieu va)) phap tu va ((kinh vai) OR (kinh hai)) cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thieu khang xa hoi. ((hieu van) OR (hieu va)) phap tu va ((kinh vai) OR (kinh hai)) cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thieu khang xa hoi. ((hieu van) or (hieu va)) phap tu va ((kinh vai) OR (kinh hai)) cu tren".
• Adding a wildcard symbol may retrieve word variants: tu sach thieu khang xa hoi. ((hieu van) or (hieu va)) phap tu va ((kinh vai) OR (kinh hai)) cu tren*.