Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
hoc van » hoc dan, hoc va, hoc vat
vu kham » vu khanh
vu cham » va cham, tu cham, qua cham
mang xa » lang xa, mang may, dang xay
xang xa » lang xa, ang xa, dang xay
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 y ((xang xa) OR (mang xa)) hoi. hieu ((vu cham) or (vu kham)) hoc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((xang xa) OR (mang xa)) hoi. hieu ((vu cham) OR (vu kham)) hoc van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((xang xa) OR (mang xa)) hoi. hieu ((vu cham) or (vu kham)) hoc van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((xang xa) OR (mang xa)) hoi. hieu ((vu cham) or (vu kham)) hoc van hanh vi cua tre*.