Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
dang xay » dang van, van xay
thu ngan » tu ngan, vu ngan, tu ngay
lang xa » lang ha, lang van
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
hang vi » hang va, hanh vi, hang di
tu sach » thu sach, su sach, te sach
va cau » van cau, va cac, va dau
vi cau » ve cau, di cau, viet cau

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 ty ((lang xa) or (dang xay)) hoi. hieu va cau ((thu ngan) OR (tai ngan)) hang vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((lang xa) OR (dang xay)) hoi. hieu va cau ((thu ngan) OR (tai ngan)) hang vi cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((lang xa) or (dang xay)) hoi. hieu va cau ((thu ngan) OR (tai ngan)) hang vi cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((lang xa) or (dang xay)) hoi. hieu va cau ((thu ngan) OR (tai ngan)) hang vi cau tren*.