Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, tu cach
nang ma » tang ma, sang ma, nang cao
mua van » ma van, mua ban, mua dan
nam mua » nam cua, nam qua, nam xua
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
te sach » toc sach
nang xa » nang x, lang xa, mang xa
va nam » van nam, ha nam, va nay
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 (te sach)) y ((nang xa) or (nang ma)) hoi. hieu va nam mua van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) y ((nang xa) OR (nang ma)) hoi. hieu va nam mua van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (te sach)) y ((nang xa) or (nang ma)) hoi. hieu va nam mua van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (te sach)) y ((nang xa) or (nang ma)) hoi. hieu va nam mua van hanh vi cua tre*.