Perhaps you should try some spelling variations:
cau theo » cau thi, cau tao
van hanh » van thanh, ban hanh, van anh
hoc van » hoc dan, hoc va, hoc vat
coc hoc » co hoc, toc hoc, hoc hoc
hieu va » lieu va, hieu qua
hieu ve » hieu van
nang xa » nang x, lang xa, nang ma
sach v » sach va, sach 2, sach vay
vi cau » va cau, ve cau, di cau

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach v) OR (sach y)) nang xa hoi. ((hieu ve) OR (hieu va)) coc hoc van hanh vi cau theo~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach v) or (sach y)) nang xa hoi. ((hieu ve) OR (hieu va)) coc hoc van hanh vi cau theo~".
• Adding a wildcard symbol may retrieve word variants: tu ((sach v) or (sach y)) nang xa hoi. ((hieu ve) OR (hieu va)) coc hoc van hanh vi cau theo*.