Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
toc sach » hoc sach, doc sach, thuoc sach
nang mai » nang ma, nang tai, lang mai
tu sach » thu sach, su sach, te sach
luc van » luoc van, luu van, duc van
cau luc » cau truc, cau phuc
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
mai hoi » mai khoi, dai hoi, lai hoi
y nang » ky nang, ly nang, v nang
vi cua » vai cua, di cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (toc sach)) y nang mai hoi. ((hieu ve) or (lieu va)) cau luc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (toc sach)) y nang mai hoi. ((hieu ve) OR (lieu va)) cau luc van hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (toc sach)) y nang mai hoi. ((hieu ve) or (lieu va)) cau luc van hanh vi cua tre*.