Perhaps you should try some spelling variations:
phat duc » pham duc, phan duc, phan duoc
tu sach » thu sach, su sach, te sach
cua tre » cua te, cua triet, dua tren
danh vi » dinh vi, danh di, danh va
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
hieu va » lieu va, hieu qua
cuu tre » cau tren, cau treo
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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 ty nang o hoi. hieu va phat duc va ((danh vi) OR (hanh vi)) ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang o hoi. hieu va phat duc va ((danh vi) OR (hanh vi)) ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang o hoi. hieu va phat duc va ((danh vi) OR (hanh vi)) ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang o hoi. hieu va phat duc va ((danh vi) OR (hanh vi)) ((cua tre) or (cuu tre))*.