Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, va tinh
thanh di » thanh doi, thanh de, thanh do
sach ky » sac ky, sach ty, sach kem
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc ((sach ky) OR (sach y)) nang ma hoi. hieu va ((tao duoc) or (giao duc)) va thanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc ((sach ky) OR (sach y)) nang ma hoi. hieu va ((tao duoc) OR (giao duc)) va thanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc ((sach ky) OR (sach y)) nang ma hoi. hieu va ((tao duoc) or (giao duc)) va thanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: thuoc ((sach ky) OR (sach y)) nang ma hoi. hieu va ((tao duoc) or (giao duc)) va thanh di cua tre*.