Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh dai » hanh tai, hanh dao, vanh dai
van hanh » van thanh, ban hanh, van anh
dang xay » dang van, van xay
pham thu » pham thuc, pham thi, phap thu
pham tu » phan tu, pham thi, pham tai
hieu ve » hieu va, hieu van
lang xa » lang ha, lang van
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 (dang xay)) hoi. hieu ve ((pham thu) or (pham tu)) van hanh dai cua tuc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((lang xa) OR (dang xay)) hoi. hieu ve ((pham thu) OR (pham tu)) van hanh dai cua tuc.
• Adding a wildcard symbol may retrieve word variants: toc sach y ((lang xa) or (dang xay)) hoi. hieu ve ((pham thu) or (pham tu)) van hanh dai cua tuc*.