Perhaps you should try some spelling variations:
nhieu viec » hieu viec, nhien viet
toc sach » hoc sach, doc sach, thuoc sach
thuc can » thuc chan, thuc dan, thuc van
dan thuc » dan toc, am thuc
viec dan » viec dang, viec ban, viec dat
can dan » canh dan, cac dan, can ban
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
dan vi » doan vi, don vi, dan 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: ((te sach) OR (toc sach)) tu ((nang xa) or (nang ma)) hoi. nhieu viec dan thuc can dan 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 can dan 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 can dan 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 can dan vi cua tre*.