Perhaps you should try some spelling variations:
sach tham » sach nha
toc sach » hoc sach, doc sach, thuoc sach
hanh tai » thanh tai, hang tai, han tai
hanh vai » hanh vi, hanh va, hanh van
cac luc » cau luc, coc luc, cac nuoc
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
lang xa » lang ha, dang xay, lang van
cua tre » cua te, cuu tre, cua triet
luc va » duc va, tuc va, loc va

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 tham ((lang xa) or (nang ma)) hoi. hieu va cac luc va ((hanh vai) OR (hanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach tham ((lang xa) OR (nang ma)) hoi. hieu va cac luc va ((hanh vai) OR (hanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach tham ((lang xa) or (nang ma)) hoi. hieu va cac luc va ((hanh vai) OR (hanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach tham ((lang xa) or (nang ma)) hoi. hieu va cac luc va ((hanh vai) OR (hanh tai)) cua tre*.