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
van hanh » van thanh, ban hanh, van anh
vu sach » vu bach, su sach, vu khach
hieu va » lieu va, hieu qua
hanh de » hanh ve, hanh kem
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
nang o » nang co, nang ho, nang ro
va cau » van cau, va cac, va dau
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: vu sach van nang o hoi. hieu va cau truc van hanh de ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach van nang o hoi. hieu va cau truc van hanh de ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: vu sach van nang o hoi. hieu va cau truc van hanh de ((cua tre) or (cuu tre))*.