Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
qua dau » qua da, qua bau, qua dan
dau xua » dau cua, dao xuan, dau luan
xua van » xua va, qua van, cua van
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van 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 (thu hoach)) ((y nang) OR (v nang)) xa hoi. hieu qua dau xua van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu hoach)) ((y nang) OR (v nang)) xa hoi. hieu qua dau xua van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu hoach)) ((y nang) OR (v nang)) xa hoi. hieu qua dau xua van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu hoach)) ((y nang) OR (v nang)) xa hoi. hieu qua dau xua van hanh vi cua tre*.