Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh dao » lanh dao, thanh dat, thanh dam
van hanh » van thanh, ban hanh, van anh
pham thu » pham thuc, pham thi, phap thu
hieu ve » hieu va, hieu van
pham tu » phan tu, pham thi, pham tai
lang xa » lang ha, dang xay, lang van
dao cua » dai cua, day cua, dan cua
cua tuc » cua duc, cua tu, cua thuoc

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) OR (pham tu)) van hanh dao cua tuc~.
• 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) OR (pham tu)) van hanh dao cua tuc.
• 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) OR (pham tu)) van hanh dao cua tuc".
• Adding a wildcard symbol may retrieve word variants: toc sach y ((lang xa) or (van xay)) hoi. hieu ve ((pham thu) OR (pham tu)) van hanh dao cua tuc*.