Perhaps you should try some spelling variations:
thanh di » thanh doi, thanh de, thanh do
hieu van » hieu va, thien van, lieu va
thuc va » thuc vat, thuc dan, thuc day
sach ky » sac ky, sach y, sach kem
van cam » van nam, van lam, van cau
sach ty » sach y, sach tu, sach thu
nang o » nang co, nang ho, nang ro
tuc va » truc va, tuc xa, duc va
di cua » dai cua, doi cua, de cua
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 ky) OR (sach ty)) nang o hoi. hieu van cam ((tuc va) or (thuc va)) thanh di cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach ky) OR (sach ty)) nang o hoi. hieu van cam ((tuc va) OR (thuc va)) thanh di cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sach ky) OR (sach ty)) nang o hoi. hieu van cam ((tuc va) or (thuc va)) thanh di cua te".
• Adding a wildcard symbol may retrieve word variants: so ((sach ky) OR (sach ty)) nang o hoi. hieu van cam ((tuc va) or (thuc va)) thanh di cua te*.