Perhaps you should try some spelling variations:
sach truc » cach thuc, sach tren, sach thu
bac truc » ba truc, bac trung, cau truc
doanh va » doan va, doanh tai, doanh cua
va doanh » van doanh, vay doanh, va danh
dang xay » dang van, van xay
hieu van » hieu va, thien van, lieu va
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
va cua » va chua, via cua, ca cua
cua te » cua tu

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 ((nang xa) or (dang xay)) hoi. hieu van ((bac truc) OR (sach truc)) va doanh va cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((nang xa) OR (dang xay)) hoi. hieu van ((bac truc) OR (sach truc)) va doanh va cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((nang xa) or (dang xay)) hoi. hieu van ((bac truc) OR (sach truc)) va doanh va cua te*".