Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
thuoc va » thuc va, thuoc ma, thuong va
sach thu » sach thue, sach thieu, sach tham
hieu van » hieu va, thien van, lieu va
nang ma » tang ma, sang ma, nang cao
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: thuat sach thu ((nang ma) or (nang x)) hoi. hieu van nam ((thuoc va) or (thuc vat)) tinh ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach thu ((nang ma) OR (nang x)) hoi. hieu van nam ((thuoc va) OR (thuc vat)) tinh ca cua tre.
• Adding a wildcard symbol may retrieve word variants: thuat sach thu ((nang ma) or (nang x)) hoi. hieu van nam ((thuoc va) or (thuc vat)) tinh ca cua tre*.