Perhaps you should try some spelling variations:
nhieu viec » hieu viec, nhien viet
toc sach » hoc sach, doc sach, thuoc sach
thuc cao » thuoc cao, thuc co, thuc can
dan thuc » dan toc, am thuc
viec dan » viec dang, viec ban, viec dat
dang vi » dung vi, dang va, hang vi
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
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: ((te sach) OR (toc sach)) tu ((nang xa) or (nang ma)) hoi. nhieu viec dan thuc cao dang vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) tu ((nang xa) OR (nang ma)) hoi. nhieu viec dan thuc cao dang vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) tu ((nang xa) or (nang ma)) hoi. nhieu viec dan thuc cao dang vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) tu ((nang xa) or (nang ma)) hoi. nhieu viec dan thuc cao dang vi cua tre*.