Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
cam thuc » am thuc, nam thuc, cam thu
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, te sach, vu sach
hanh de » hanh ve, hanh kem
van cam » van nam, van lam, van cau
tang ha » lang ha, tang ma, trung ha
ky tang » ky nang, ky dang, kho tang
su sach » so sach, vu sach
tu cach » tu cac
cua tre » cua te, cuu tre, cua triet
de cua » le cua, te cua, dieu cua

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) or (tu cach))) or (su sach)) ky tang ha noi. hieu van cam thuc van hanh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((tu sach) OR (tu cach))) OR (su sach)) ky tang ha noi. hieu van cam thuc van hanh de cua tre.
• Adding a wildcard symbol may retrieve word variants: ((((tu sach) or (tu cach))) or (su sach)) ky tang ha noi. hieu van cam thuc van hanh de cua tre*.