Perhaps you should try some spelling variations:
thuc dan » thuc hanh, hoc dan, thuc vat
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
duc van » duc tan, duc manh, duc phan
hanh va » hang va, hanh vi
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
nang o » nang co, nang ho, nang ro
ve cac » va cac, vien cac
va cua » va chua, via cua, ca cua
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 y nang o hoi. hieu ve cac ((thuc dan) or (((duc van) or (duc va)))) hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang o hoi. hieu ve cac ((thuc dan) OR (((duc van) OR (duc va)))) hanh va cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach y nang o hoi. hieu ve cac ((thuc dan) or (((duc van) or (duc va)))) hanh va cua tre*.