Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
thanh dai » thanh hai, thanh tai, thanh dat
mai khoi » mai khoa, tai khoa, cac khoi
doc sach » hoc sach, toc sach, nuoc sach
cau thuc » cau truc, cuu thuc, can thuc
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa
va cau » van cau, va cac, va dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach y nang ((ma hoi) or (mai khoi)). hieu va cau thuc vat thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach y nang ((ma hoi) OR (mai khoi)). hieu va cau thuc vat thanh dai cua tre.
• Adding a wildcard symbol may retrieve word variants: doc sach y nang ((ma hoi) or (mai khoi)). hieu va cau thuc vat thanh dai cua tre*.