Perhaps you should try some spelling variations:
sach van » sach han, sach va, bach van
van nang » van quang, van ban, van dong
truc van » truc va, thuc van, truc ban
su sach » so sach, vu sach
hanh de » hanh ve
hieu va » lieu va, hieu qua
hieu ve » hieu van
nang o » nang co, nang ho, nang ro
cua te » cua tu
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: su sach van nang o hoi. ((hieu ve) OR (hieu va)) cau truc van ((hanh de) or (hanh kem)) cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach van nang o hoi. ((hieu ve) OR (hieu va)) cau truc van ((hanh de) OR (hanh kem)) cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach van nang o hoi. ((hieu ve) OR (hieu va)) cau truc van ((hanh de) or (hanh kem)) cua te".
• Adding a wildcard symbol may retrieve word variants: su sach van nang o hoi. ((hieu ve) OR (hieu va)) cau truc van ((hanh de) or (hanh kem)) cua te*.