Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
doanh va » doan va, doanh tai, doanh cua
va doanh » van doanh, vay doanh, va danh
dang xay » dang van, van xay
sach ky » sac ky, sach y, sach ty
van bac » van bao, van hac, dan bac
truc va » thuc va, thuc vat, trung va
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: toc sach ky ((nang xa) or (dang xay)) hoi. hieu ((van bac) OR (van ban)) truc va doanh va cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((nang xa) OR (dang xay)) hoi. hieu ((van bac) OR (van ban)) truc va doanh va cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky ((nang xa) or (dang xay)) hoi. hieu ((van bac) OR (van ban)) truc va doanh va cua te*".