Perhaps you should try some spelling variations:
trinh vat » trinh van, trinh luat, sinh vat
thien van » thi van
nam thuc » nam thuoc, am thuc, nam thu
thuc va » thuc vat, thuc dan, thuc day
tinh va » tich va, trinh van, tinh gia
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
nang xa » lang xa, nang ma, mang xa
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: tu sach ty ((nang xa) or (nang x)) hoi. thien van nam thuc va ((tinh va) OR (trinh vat)) 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 va ((tinh va) OR (trinh vat)) 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 va ((tinh va) OR (trinh vat)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang xa) or (nang x)) hoi. thien van nam thuc va ((tinh va) OR (trinh vat)) cua tre*.