Perhaps you should try some spelling variations:
va thanh » ban thanh, va tinh, le thanh
nang tai » hang tai, tang tai, sang tai
tai khoa » da khoa, noi khoa
so sach » so sanh, bo sach, co sach
dao cuu » dao huu, dao cau, dao chu
hieu va » lieu va, hieu qua
hieu ve » hieu van
cuu tre » cua tre, cau tren, cau treo
y nang » ky nang, ly nang, v nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y nang tai khoa. ((hieu ve) or (hieu va)) coc luc ((va thanh) or (gia thanh)) dao cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y nang tai khoa. ((hieu ve) OR (hieu va)) coc luc ((va thanh) OR (gia thanh)) dao cuu tre.
• Adding a wildcard symbol may retrieve word variants: so sach y nang tai khoa. ((hieu ve) or (hieu va)) coc luc ((va thanh) or (gia thanh)) dao cuu tre*.