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