Perhaps you should try some spelling variations:
thanh dinh » thanh binh, thanh tinh, thanh vinh
hanh dinh » hinh dinh, hanh tinh, anh dinh
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
thuc va » thuc vat, thuc dan, thuc day
cuu tre » cua tre, cau tren, cau treo
sach ty » sach y, sach tu, sach thu
truc va » thuc vat, trung va
van cam » van nam, van lam, van cau
xang o » lang o, tang o, dang o
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: tu sach ty xang o hoi. hieu van cam ((truc va) or (thuc va)) ((hanh dinh) OR (thanh dinh)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty xang o hoi. hieu van cam ((truc va) OR (thuc va)) ((hanh dinh) OR (thanh dinh)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty xang o hoi. hieu van cam ((truc va) or (thuc va)) ((hanh dinh) OR (thanh dinh)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty xang o hoi. hieu van cam ((truc va) or (thuc va)) ((hanh dinh) OR (thanh dinh)) cuu tre*.