Perhaps you should try some spelling variations:
manh xanh » mang xanh, manh binh, manh tinh
hieu van » hieu va, thien van, lieu va
van pham » san pham, van phan, van phat
cua viet » ca viet, hoa viet, cua vat
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
anh anh » thanh anh, hinh anh, minh anh
di cua » dai cua, doi cua, de cua
x hoi » xa hoi, x ho, 5 hoi
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 ky nang ((x hoi) or (o hoi)). hieu van pham duc ((manh xanh) OR (anh anh)) di cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (o hoi)). hieu van pham duc ((manh xanh) OR (anh anh)) di cua viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((x hoi) or (o hoi)). hieu van pham duc ((manh xanh) OR (anh anh)) di cua viet*".