Perhaps you should try some spelling variations:
thanh doi » thanh loi, thanh moi, thanh do
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, co sach
van cam » van nam, van lam, van cau
thuc va » thuc vat, thuc dan, thuc day
doi cua » dai cua, hoi cua
y nang » ky nang, ly nang, v nang
nang o » nang co, nang ho, nang ro
tuc va » truc va, tuc xa, duc va
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: so sach y nang o hoi. hieu van cam ((tuc va) or (thuc va)) thanh doi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y nang o hoi. hieu van cam ((tuc va) OR (thuc va)) thanh doi cua te.
• Adding a wildcard symbol may retrieve word variants: so sach y nang o hoi. hieu van cam ((tuc va) or (thuc va)) thanh doi cua te*.