Perhaps you should try some spelling variations:
nhien hoc » nhiet hoc, khien hoc, dien hoc
hanh dai » hanh tai, hanh dao, vanh dai
sach ky » sac ky, sach ty, sach kem
anh tay » canh tay, anh ta, anh hay
tay hoi » tay ho, tao hoi, tay thai
quoc va » nuoc va, duoc va, quoc oai
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach ky) OR (sach y)) anh tay hoi. thien nhien hoc ((quoc va) or (quoc gia)) hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sach y)) anh tay hoi. thien nhien hoc ((quoc va) OR (quoc gia)) hanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ky) OR (sach y)) anh tay hoi. thien nhien hoc ((quoc va) or (quoc gia)) hanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach ky) OR (sach y)) anh tay hoi. thien nhien hoc ((quoc va) or (quoc gia)) hanh dai cua tre*.