Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
lang van » dang van, tang van, hoang van
dang xay » dang van, van xay
van hanh » van thanh, ban hanh, van anh
hanh di » hanh vi, hanh de, hang di
cua tuc » cua duc, cua tu, cua thuoc
hieu ve » hieu va, hieu van
cac tuc » cac toc, cac tu, cac tac
tuc van » thuc van, truc van, tuc va
ve cac » va cac, vien cac
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 y ((lang van) or (dang xay)) hoi. hieu ve cac tuc van hanh di ((cua tuc) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((lang van) OR (dang xay)) hoi. hieu ve cac tuc van hanh di ((cua tuc) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: toc sach y ((lang van) or (dang xay)) hoi. hieu ve cac tuc van hanh di ((cua tuc) or (cua te))*.