Perhaps you should try some spelling variations:
thuoc va » thuoc ma, thuong va, thuoc tai
sach thu » sach thue, sach thieu, sach tham
hieu van » hieu va, thien van, lieu va
thu sach » tu sach, thuat sach, thuoc sach
nang ma » tang ma, sang ma, nang cao
thuc va » thuc vat, thuc dan, thuc day
tinh ca » tinh cao, tinh cua, tinh va
cua tre » cua te, cuu tre, cua triet
ca cua » co cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach thu ((nang ma) or (nang x)) hoi. hieu van nam ((thuoc va) OR (thuc va)) tinh ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach thu ((nang ma) OR (nang x)) hoi. hieu van nam ((thuoc va) OR (thuc va)) tinh ca cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach thu ((nang ma) or (nang x)) hoi. hieu van nam ((thuoc va) OR (thuc va)) tinh ca cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach thu ((nang ma) or (nang x)) hoi. hieu van nam ((thuoc va) OR (thuc va)) tinh ca cua tre*.