Perhaps you should try some spelling variations:
doc sach » toc sach, nuoc sach, dac sac
hoc sach » hoc sinh, hoc cac, hoc anh
tru nang » tra nang, tri nang, truc nano
va hanh » van hanh, va thanh, va danh
cao tuc » dao tuc, cao duc, cao suc
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
va cao » va cac, va co, va dao
tuc va » thuc va, truc va, tuc xa
vi cua » vai cua
di cua » dai cua, doi cua, de cua

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)) tru nang xa hoi. hieu va cao tuc va hanh ((vi cua) OR (di cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sach) OR (hoc sach)) tru nang xa hoi. hieu va cao tuc va hanh ((vi cua) OR (di cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc sach) or (hoc sach)) tru nang xa hoi. hieu va cao tuc va hanh ((vi cua) OR (di cua)) tre".
• Adding a wildcard symbol may retrieve word variants: ((doc sach) or (hoc sach)) tru nang xa hoi. hieu va cao tuc va hanh ((vi cua) OR (di cua)) tre*.