Perhaps you should try some spelling variations:
dan tinh » doan tinh, dang tinh, dan trinh
thuc dan » thuc hanh, hoc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, tu cach
tinh va » tich va, trinh van, trinh vat
cua tre » cua te, cuu tre, cua triet
nang xa » lang xa, nang ma, mang xa
te sach » toc sach
va cua » va chua, via cua, ca cua

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