Perhaps you should try some spelling variations:
thai cuu » thai cua, tai cuc, thi cuc
dan thai » dang thai, dan thi, dan than
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
cac toc » cac toi, cac nuoc, cac thoi
cac tac » cac bac, cac dac, cac tai
cuu tre » cua tre, cau tren, cau treo
cac tuc » cac tu, cac nuoc, cac cuoc
ty nang » ky nang, ty xang, ty hang
va dan » ca dan, va dao, va dau
x hoi » xa hoi, o hoi, x ho

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