Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
hieu van » hieu va, thien van, lieu va
doc sach » hoc sach, nuoc sach, dac sac
nang ma » tang ma, sang ma, nang cao
van hau » van ha, van hai, van dau
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
v nang » va nang, vu nang, van nang
ma hoi » mai hoi, xa hoi, ma hoa

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) OR (doc sach)) v nang ma hoi. hieu 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) OR (doc sach)) v nang ma hoi. hieu 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) OR (doc sach)) v nang ma hoi. hieu van hau duc van ((hanh ve) or (hanh kem)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) v nang ma hoi. hieu van hau duc van ((hanh ve) or (hanh kem)) cuu tre*.