Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cham hoc » cham soc, chat hoc, cham hoi
lang van » dang van, tang van, hoang van
te sach » toc sach
luu tre » cuu tre, luy tre
hoc van » hoc dan, hoc va, hoc vat
va cham » va chat, va tham
hieu va » lieu va, hieu qua
sach ty » sach y, sach tu, sach thu
mang xa » lang xa, mang may, dang xay
tru » truc

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