Perhaps you should try some spelling variations:
so sach » so sanh, bo sach, co sach
ky lang » ky nang, ky tang, tay lang
ky dang » ky nang, ky danh
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
va hanh » van hanh, va thanh, va danh
vai cua » dai cua, hai cua, lai cua
tuc va » thuc va, truc va, tuc xa
de cua » le cua, te cua, dieu cua

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 ((ky lang) OR (ky dang)) xa hoi. hieu va cac tuc va hanh ((de cua) or (vai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ky lang) OR (ky dang)) xa hoi. hieu va cac tuc va hanh ((de cua) OR (vai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ky lang) OR (ky dang)) xa hoi. hieu va cac tuc va hanh ((de cua) or (vai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((ky lang) OR (ky dang)) xa hoi. hieu va cac tuc va hanh ((de cua) or (vai cua)) tre*.