Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
pham thu » pham thuc, pham thi, pham tu
van hanh » van thanh, ban hanh, van anh
hanh dao » lanh dao, thanh dat, thanh dam
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
thu van » thuc van, thuy van, tu van
cua tuc » cua tu, cua thuoc, luat tuc
cua duc » cua nuoc, cua quoc

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 y ((lang xa) or (van xay)) hoi. hieu ve pham thu van hanh dao ((cua tuc) OR (cua duc))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((lang xa) OR (van xay)) hoi. hieu ve pham thu van hanh dao ((cua tuc) OR (cua duc)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y ((lang xa) or (van xay)) hoi. hieu ve pham thu van hanh dao ((cua tuc) OR (cua duc))".
• Adding a wildcard symbol may retrieve word variants: toc sach y ((lang xa) or (van xay)) hoi. hieu ve pham thu van hanh dao ((cua tuc) OR (cua duc))*.