Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, le thanh
dang xay » dang van, van xay
te sach » toc sach
sach ky » sac ky, sach y, sach ty
va tinh » may tinh
cac thu » cach thuc, cac thoi
cu tren » tu tren, dua tren
hieu ve » hieu va, hieu van
lang ha » long ha
ve cac » va cac, vien 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: te sach ky ((dang xay) or (lang ha)) hoi. hieu ve cac thu ((va thanh) OR (va tinh)) vi cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((dang xay) OR (lang ha)) hoi. hieu ve cac thu ((va thanh) OR (va tinh)) vi cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((dang xay) or (lang ha)) hoi. hieu ve cac thu ((va thanh) OR (va tinh)) vi cu tren".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((dang xay) or (lang ha)) hoi. hieu ve cac thu ((va thanh) OR (va tinh)) vi cu tren*.