Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nang xa » nang x, lang xa, nang ma
van cam » van nam, van lam, van cau
cam duc » cam xuc, cao duc, pham duc
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
cau tre » cau tren, cau treo, cau tra
y nang » ky nang, ly nang, v nang
ca tra » cau tra, ca tru, va tra

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 xa hoi. hieu van cam duc va hanh di ((cau tre) or (ca tra))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang xa hoi. hieu van cam duc va hanh di ((cau tre) OR (ca tra)).
• Adding a wildcard symbol may retrieve word variants: toc sach y nang xa hoi. hieu van cam duc va hanh di ((cau tre) or (ca tra))*.