Perhaps you should try some spelling variations:
duy hoang » huy hoang, duc hoang, duy thong
ky hoang » huy hoang, ky nang, le hoang
te sach » toc sach
van hoc » van hoa
qua dat » quy dat, qua da, qua dan
hanh di » hanh de, hang di, danh di
cua tre » cua te, cuu tre, cua triet
nuoc » quoc, duoc, ngoc

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 hoang) or (duy hoang)) van hoc. hieu qua dat nuoc va ((hanh di) OR (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ky hoang) OR (duy hoang)) van hoc. hieu qua dat nuoc va ((hanh di) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ky hoang) or (duy hoang)) van hoc. hieu qua dat nuoc va ((hanh di) OR (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ((ky hoang) or (duy hoang)) van hoc. hieu qua dat nuoc va ((hanh di) OR (hanh vi)) cua tre*.