Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
tu sach » su sach, te sach, tu cach
ty nang » ky nang, ty xang, ty hang
hieu va » lieu va, hieu qua
va pham » van pham, va phat, va phap
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
cua tre » cuu tre, cua triet, dua tren
cua te » cua tu
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) or (thu sach)) ty nang x hoi. hieu va pham duc va danh vi ((cua tre) OR (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ty nang x hoi. hieu va pham duc va danh vi ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ty nang x hoi. hieu va pham duc va danh vi ((cua tre) OR (cua te))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ty nang x hoi. hieu va pham duc va danh vi ((cua tre) OR (cua te))*.