Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cua triet, dua tren
luu van » cuu van, luan van, luu hanh
cuu tre » cau tren, cau treo
ve cam » ve cham, va cam, ve cai
ve cac » va cac, vien cac
x hoi » xa hoi, o hoi, x ho

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 ky nang x hoi. hieu ((ve cam) or (ve cac)) luu van hanh vi ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu ((ve cam) OR (ve cac)) luu van hanh vi ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. hieu ((ve cam) or (ve cac)) luu van hanh vi ((cua tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu ((ve cam) or (ve cac)) luu van hanh vi ((cua tre) OR (cuu tre))*.