Perhaps you should try some spelling variations:
tinh van » trinh van, dinh van, tinh va
te sach » toc sach
hieu va » lieu va, hieu qua
va cham » va chat, va tham
van cua » vang cua, ban cua, dan cua
y hang » ly hang, ty hang, yu hang
hang o » hang do, hang o2, hoang o
doc va » duoc va, duc va, loc va
cua cu » cua chu, cua cau, cua su
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach y hang o hoi. hieu va cham ((doc va) or (hoc va)) tinh van cua cu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y hang o hoi. hieu va cham ((doc va) OR (hoc va)) tinh van cua cu.
• Adding a wildcard symbol may retrieve word variants: te sach y hang o hoi. hieu va cham ((doc va) or (hoc va)) tinh van cua cu*.