Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
doc sach » hoc sach, toc sach, nuoc sach
va thanh » gia thanh, ban thanh, va tinh
cam truc » cau truc, nam truc, lam truoc
mai khoi » mai khoa, tai khoa, cac khoi
hieu va » lieu va, hieu qua
truc va » thuc va, thuc vat, trung va
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
va cam » va cham, va cac, va cao
ma hoi » mai hoi, xa hoi, me hoi

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 (ma hoa))) or (mai khoi)). hieu va cam truc va thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach y nang ((((ma hoi) OR (ma hoa))) OR (mai khoi)). hieu va cam truc va thanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach y nang ((((ma hoi) OR (ma hoa))) or (mai khoi)). hieu va cam truc va thanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: doc sach y nang ((((ma hoi) OR (ma hoa))) or (mai khoi)). hieu va cam truc va thanh dai cua tre*.