Perhaps you should try some spelling variations:
cach thuc » anh thuc, cac thu
hieu van » hieu va, thien van, hieu ve
thuc day » thuc dan, thuc vat
day tinh » may tinh, dac tinh, dao tinh
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
tinh va » tich va, trinh van, trinh vat
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
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: thu ((sach ky) or (cac ky)) nang ma hoi. ((hieu van) or (lieu va)) cach thuc day tinh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (cac ky)) nang ma hoi. ((hieu van) OR (lieu va)) cach thuc day tinh va cua tre.
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (cac ky)) nang ma hoi. ((hieu van) or (lieu va)) cach thuc day tinh va cua tre*.