Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cua viet » ca viet, hoa viet, cua vat
sach ty » sach y, sach tu, sach thu
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
thi van » thi lan, thi hanh, thi nang
van bac » van ban, van bao, van hac
hai cua » thai cua, dai cua, hoi cua

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 ty ((nang xa) or (lang xa)) hoi. thi van bac xuc ((va tinh) OR (may tinh)) hai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((nang xa) OR (lang xa)) hoi. thi van bac xuc ((va tinh) OR (may tinh)) hai cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty ((nang xa) or (lang xa)) hoi. thi van bac xuc ((va tinh) OR (may tinh)) hai cua viet".
• Adding a wildcard symbol may retrieve word variants: toc sach ty ((nang xa) or (lang xa)) hoi. thi van bac xuc ((va tinh) OR (may tinh)) hai cua viet*.