Perhaps you should try some spelling variations:
nhanh thuc » nhan thuc, thanh thuy, anh thuc
nhanh thi » nhanh thai, nhan tai, nhanh ha
duc manh » suc manh, duc anh, duc minh
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
co hoi » co hoc, co loi
o hoi » o hoc, o hai, 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: tu sach ty nang ((o hoi) or (co hoi)). hieu van cau duc manh ((nhanh thi) OR (nhanh thuc)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ((o hoi) OR (co hoi)). hieu van cau duc manh ((nhanh thi) OR (nhanh thuc)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ((o hoi) or (co hoi)). hieu van cau duc manh ((nhanh thi) OR (nhanh thuc)) cua tre*".