Perhaps you should try some spelling variations:
hoc viet » hoc hien
hieu van » hieu va, thien van, lieu va
cua viet » hoa viet, cua vat, cua dieu
lanh hai » manh hai, thanh hai, lang chai
tan lanh » tai lanh, thanh lanh, tan thanh
van cac » van hac, van cau, van bac
cac duc » cac du, cao duc, cac dac
sach ty » sach y, sach tu, sach thu
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
ca viet » va viet, co viet, hoa viet
so sach » so sanh, bo sach, co sach

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ty nang xa hoi. hieu van cac duc tan lanh hai ((cua viet) or (((ca viet) or (hoc viet))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty nang xa hoi. hieu van cac duc tan lanh hai ((cua viet) OR (((ca viet) OR (hoc viet)))).
• Adding a wildcard symbol may retrieve word variants: so sach ty nang xa hoi. hieu van cac duc tan lanh hai ((cua viet) or (((ca viet) or (hoc viet))))*.