Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cham sat » cham mat, cham soc, khao sat
lang van » dang van, tang van, hoang van
te sach » toc sach
sat van » sat va, hat van, hoat van
sach ky » sac ky, sach y, sach ty
hieu va » lieu va
mang xa » lang xa, mang may, dang xay
luy tre » luyen tre
vi luy » vi lua, vi luu

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: te sach ky ((mang xa) OR (lang van)) hoi. ((hieu va) OR (hieu qua)) cham sat van hanh vi luy tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((mang xa) or (lang van)) hoi. ((hieu va) OR (hieu qua)) cham sat van hanh vi luy tre~".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((mang xa) or (lang van)) hoi. ((hieu va) OR (hieu qua)) cham sat van hanh vi luy tre*.