Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
nang tai » hang tai, tang tai, sang tai
hieu van » hieu va, thien van, lieu va
van tham » van thanh, van tuan, van chat
danh dai » danh dau, danh di, danh sai
sach ky » sac ky, sach ty, sach kem
tai hoi » tai khoi, dai hoi, tai hai
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
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: toc ((sach ky) or (sach y)) nang tai hoi. hieu van tham thuc va danh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach ky) OR (sach y)) nang tai hoi. hieu van tham thuc va danh dai cua tre.
• Adding a wildcard symbol may retrieve word variants: toc ((sach ky) or (sach y)) nang tai hoi. hieu van tham thuc va danh dai cua tre*.