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