Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, hieu ve
sach ky » sac ky, sach y, sach ty
nang du » nang tu, nang luc, nang doc
va hanh » van hanh, va thanh, va danh
du hoi » du hoc, lu hoi, di hoi
xuc va » duc va, tuc va, luc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky nang du hoi. ((hieu van) or (lieu va)) cam xuc va hanh ((vi luu) OR (vi lua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang du hoi. ((hieu van) OR (lieu va)) cam xuc va hanh ((vi luu) OR (vi lua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang du hoi. ((hieu van) or (lieu va)) cam xuc va hanh ((vi luu) OR (vi lua)) tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang du hoi. ((hieu van) or (lieu va)) cam xuc va hanh ((vi luu) OR (vi lua)) tre*.