Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
vat thanh » dat thanh, gat thanh, tat thanh
sach vay » sach va, sach hay, sach nay
cam thuc » am thuc, nam thuc, cam thu
hieu van » hieu va, thien van, lieu va
hai cua » thai cua, dai cua, hoi cua
van cam » van nam, van lam, van cau
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
sach v » sach va, sach 2
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((((sach v) OR (sach vay))) or (sach y)) nang ma hoi. hieu van cam thuc vat thanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((((sach v) OR (sach vay))) OR (sach y)) nang ma hoi. hieu van cam thuc vat thanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((((sach v) OR (sach vay))) or (sach y)) nang ma hoi. hieu van cam thuc vat thanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((((sach v) OR (sach vay))) or (sach y)) nang ma hoi. hieu van cam thuc vat thanh hai cua tre*.