Perhaps you should try some spelling variations:
doc sach » toc sach, nuoc sach, dac sac
hoc sach » hoc sinh, hoc cac, hoc anh
hieu van » hieu va, thien van, lieu va
cac xuc » cam xuc, cac nuoc, chat xuc
giao su » giao duc
va dinh » van dinh, va kinh, va tinh
va danh » va dan, va hanh, dia danh
van cac » van hac, van cau, van bac
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
su tien » su kien, su hien, tu tieng

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((doc sach) or (hoc sach)) ty nang xa hoi. hieu van cac xuc ((va danh) OR (va dinh)) giao su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sach) OR (hoc sach)) ty nang xa hoi. hieu van cac xuc ((va danh) OR (va dinh)) giao su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc sach) or (hoc sach)) ty nang xa hoi. hieu van cac xuc ((va danh) OR (va dinh)) giao su tien".
• Adding a wildcard symbol may retrieve word variants: ((doc sach) or (hoc sach)) ty nang xa hoi. hieu van cac xuc ((va danh) OR (va dinh)) giao su tien*.