Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
cau tren » cu tren, dau tren, ca tren
thanh vi » hanh vi, thanh va, thanh ve
chat duc » chat xuc, chat doc, chet duoc
cua tre » cua te, cuu tre, cua triet
duc ban » duc tan, duc van, dua ban
sach ty » sach y, sach tu, sach thu
so sach » so sanh, bo sach, co sach
hieu va » lieu va, hieu qua
ty nang » ky nang, ty xang, ty hang
va chat » van chat, va phat, cao chat
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o hoa

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 ((o hoi) OR (o hai)). hieu va chat duc ban thanh vi ((cua tre) OR (cau tren))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty nang ((o hoi) OR (o hai)). hieu va chat duc ban thanh vi ((cua tre) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: so sach ty nang ((o hoi) OR (o hai)). hieu va chat duc ban thanh vi ((cua tre) OR (cau tren))*.