Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
tinh va » tich va, trinh van, trinh vat
va tinh » may tinh
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
nang xa » lang xa, mang xa, ang xa
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 ty ((((nang xa) OR (nang ma))) or (nang x)) hoi. hieu van nam thuc va tinh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((((nang xa) OR (nang ma))) OR (nang x)) hoi. hieu van nam thuc va tinh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((((nang xa) OR (nang ma))) or (nang x)) hoi. hieu van nam thuc va tinh va cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((((nang xa) OR (nang ma))) or (nang x)) hoi. hieu van nam thuc va tinh va cua tre*.