Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dan than » dan chan, ban than, van than
dan thai » dang thai, dan thi, ban thai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cac tac » cac toc, cac bac, cac dac
cac tuc » cac toc, cac tu, cac nuoc
nang xa » nang x, lang xa, nang ma
cuu tre » cua tre, cau tren, cau treo

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 xa hoi. hieu van ((cac tuc) or (cac tac)) va ((dan thai) OR (dan than)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang xa hoi. hieu van ((cac tuc) OR (cac tac)) va ((dan thai) OR (dan than)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. hieu van ((cac tuc) or (cac tac)) va ((dan thai) OR (dan than)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. hieu van ((cac tuc) or (cac tac)) va ((dan thai) OR (dan than)) cuu tre*.