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

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

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