Perhaps you should try some spelling variations:
tham thuc » pham thuc, tam thuc, thai thuc
thien van » thi van
nham thuc » nhan thuc, nam thuc, nham thu
hanh hoi » hanh thoi, hanh noi, hanh hoa
day hanh » day nhanh, day thanh, dao hanh
hoi cua » hoi chuc
te sach » toc sach
cua tre » cua te, cuu tre, cua triet
nang xa » lang xa, nang ma, mang xa

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y ((nang xa) OR (nang x)) hoi. thien van ((tham thuc) OR (nham thuc)) day hanh hoi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach y ((nang xa) or (nang x)) hoi. thien van ((tham thuc) OR (nham thuc)) day hanh hoi cua tre~".
• Adding a wildcard symbol may retrieve word variants: te sach y ((nang xa) or (nang x)) hoi. thien van ((tham thuc) OR (nham thuc)) day hanh hoi cua tre*.