Perhaps you should try some spelling variations:
truc ngan » tu ngan, tri ngan, truc nano
thu sach » tu sach, thuat sach, thuoc sach
thu ngan » tu ngan, tai ngan, vu ngan
hang vi » hang va, hanh vi, hang di
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
mang xa » mang may, dang xay, mang cua
lang xa » lang ha, dang xay, lang van
cu tren » tu tren, dua tren
ve cau » ke cau, va cau, ve cac
vi cu » vi su, vi xu, vi du

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ty ((mang xa) or (lang xa)) hoi. hieu ve cau ((truc ngan) OR (thu ngan)) hang vi cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty ((mang xa) OR (lang xa)) hoi. hieu ve cau ((truc ngan) OR (thu ngan)) hang vi cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty ((mang xa) or (lang xa)) hoi. hieu ve cau ((truc ngan) OR (thu ngan)) hang vi cu tren".
• Adding a wildcard symbol may retrieve word variants: thu sach ty ((mang xa) or (lang xa)) hoi. hieu ve cau ((truc ngan) OR (thu ngan)) hang vi cu tren*.