Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
lam luc » lao luc, lam duoc
luc van » luoc van, luu van, duc van
la tren » loai tren, dua tren, dat tren
cua tre » cua te, cuu tre, cua triet
va lam » van lam, va lap

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ky lang xa hoi. lieu va lam luc van hanh vi ((la tren) or (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky lang xa hoi. lieu va lam luc van hanh vi ((la tren) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky lang xa hoi. lieu va lam luc van hanh vi ((la tren) or (cua tre))".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky lang xa hoi. lieu va lam luc van hanh vi ((la tren) or (cua tre))*.