Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
doi cua » dai cua, hoi cua
va bac » van bac, va cac, va bai
bo van » so van, do van, ho van
di cua » dai cua, de cua, do cua
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang x hoi. hieu va bac ((bo van) or (vo van)) hanh ((di cua) OR (doi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu va bac ((bo van) OR (vo van)) hanh ((di cua) OR (doi cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. hieu va bac ((bo van) or (vo van)) hanh ((di cua) OR (doi cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu va bac ((bo van) or (vo van)) hanh ((di cua) OR (doi cua)) tre*.