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 cua » dai cua, day cua, dan cua
hieu va » lieu va, hieu qua
hieu ve » hieu van
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet

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 ty nang tai khoa. ((hieu ve) or (hieu va)) coc luc ((va thanh) OR (gia thanh)) dao cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty nang tai khoa. ((hieu ve) OR (hieu va)) coc luc ((va thanh) OR (gia thanh)) dao cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty nang tai khoa. ((hieu ve) or (hieu va)) coc luc ((va thanh) OR (gia thanh)) dao cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ty nang tai khoa. ((hieu ve) or (hieu va)) coc luc ((va thanh) OR (gia thanh)) dao cua tre*.