Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
truc van » truc va, thuc van, truc ban
cam truc » cau truc, nam truc, lam truoc
su sach » so sach, vu sach
cua tre » cua te, cua triet, dua tren
hanh di » hanh vi, hanh de, hang di
cuu tre » cau tren, cau treo
hieu ve » hieu va, hieu van
nang xa » lang xa, nang ma, mang xa
sach v » sach va, sach y, sach 2
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach v ((nang xa) or (nang x)) hoi. hieu ve cam truc van hanh di ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach v ((nang xa) OR (nang x)) hoi. hieu ve cam truc van hanh di ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach v ((nang xa) or (nang x)) hoi. hieu ve cam truc van hanh di ((cua tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: su sach v ((nang xa) or (nang x)) hoi. hieu ve cam truc van hanh di ((cua tre) OR (cuu tre))*.