Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cham duc » pham duc, cham soc, pham duy
van hanh » van thanh, ban hanh, van anh
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
duc van » duc va, duc tan, duc manh
cua tre » cua te, cuu tre, cua triet
cu tren » tu tren, dua tren
y nang » ky nang, ly nang, v nang
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: toc sach y nang o hoi. hieu ve cham duc van hanh vi ((cua tre) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang o hoi. hieu ve cham duc van hanh vi ((cua tre) OR (cu tren))*.