Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
hanh van » thanh van, khanh van, hanh san
hanh va » hang va, hanh vi
duc van » duc va, duc tan, duc manh
cau duc » cao duc, cau luc, chu duc
van cau » van dau, van hau, van chat
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, ma hoa, 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: thu sach ty nang ((ma hoi) OR (xa hoi)). hieu van cau duc van ((hanh van) or (hanh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty nang ((ma hoi) OR (xa hoi)). hieu van cau duc van ((hanh van) OR (hanh va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty nang ((ma hoi) OR (xa hoi)). hieu van cau duc van ((hanh van) or (hanh va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ty nang ((ma hoi) OR (xa hoi)). hieu van cau duc van ((hanh van) or (hanh va)) cua tre*.