Perhaps you should try some spelling variations:
thien van » thi van
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, lieu va, hieu ve
nang xa » nang x, lang xa, nang ma
hau duc » huu duc, ha duc, pham duc
duc van » duc va, duc tan, duc manh
hanh ve » hanh vi, hanh va
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: toc sach y nang xa hoi. ((hieu van) OR (thien van)) hau duc van ((hanh ve) or (hanh kem)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang xa hoi. ((hieu van) OR (thien van)) hau duc van ((hanh ve) OR (hanh kem)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang xa hoi. ((hieu van) OR (thien van)) hau duc van ((hanh ve) or (hanh kem)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang xa hoi. ((hieu van) OR (thien van)) hau duc van ((hanh ve) or (hanh kem)) cuu tre*.