Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
vu sach » vu bach, su sach, vu khach
nang ma » tang ma, sang ma, nang cao
va hanh » van hanh, va thanh, va danh
cac lop » cac hop, cac loai
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, mang xa
te sach » toc sach
lop va » lap va, hop va, nop va
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: ((vu sach) or (te sach)) ky ((nang xa) OR (nang ma)) hoi. hieu vien cac lop va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu sach) OR (te sach)) ky ((nang xa) OR (nang ma)) hoi. hieu vien cac lop va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu sach) or (te sach)) ky ((nang xa) OR (nang ma)) hoi. hieu vien cac lop va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((vu sach) or (te sach)) ky ((nang xa) OR (nang ma)) hoi. hieu vien cac lop va hanh vi cua tre*.