Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cua viet » ca viet, hoa viet, cua vat
tu sach » thu sach, su sach, te sach
ky lang » ky dang, ky tang, tay lang
van cau » van dau, van hau, van chat
cau luc » cau truc, cau phuc
va hanh » van hanh, va thanh, va danh
cuu tre » cua tre, cau tren, cau treo
luc va » duc va, tuc va, loc va

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 lang) or (ky nang)) xa hoi. hieu van cau luc va hanh vi ((cuu tre) or (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky nang)) xa hoi. hieu van cau luc va hanh vi ((cuu tre) OR (cua viet)).
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) or (ky nang)) xa hoi. hieu van cau luc va hanh vi ((cuu tre) or (cua viet))*.