Perhaps you should try some spelling variations:
sach van » sach han, sach va, bach van
van tuan » van quan, van ban, anh tuan
truc van » truc va, thuc van, truc ban
su sach » so sach, vu sach
hieu ke » hieu kem, chieu ke, hieu ky
hanh de » hanh ve
tuan o » tuan do, tuan q, quan o
ke cau » ket cau
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 tuan o hoi. hieu ke 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 tuan o hoi. hieu ke cau truc van ((hanh de) OR (hanh kem)) cua te*.