Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
cham truc » cau truc, nham thuc, pham thuc
hanh doi » thanh doi, hanh noi, hang doi
van hanh » van thanh, ban hanh, van anh
truc van » truc va, thuc van, truc ban
cua tre » cua te, cuu tre, dua tren
vu sach » vu bach, su sach, vu khach
hieu ve » hieu va, hieu van
nang xa » lang xa, nang ma, mang xa
ve cham » va cham, ve chat, vu cham
sach v » sach va, sach y, sach 2

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

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