Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
phat loc » hau loc, nhat loi, phap lo
van hanh » van thanh, ban hanh, van anh
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, co hoi, tao hoi
cao hoc » co hoc, cho hoc, chat hoc
hieu va » lieu va, hieu qua
va hanh » va thanh, va danh, ban hanh
cuu tre » cua tre, cau tren, cau treo
le cuu » le cua, le huu, le cau

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 ky nang ((cao hoi) OR (cao hoc)). hieu va phat loc ((va hanh) or (van hanh)) le cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang ((cao hoi) OR (cao hoc)). hieu va phat loc ((va hanh) OR (van hanh)) le cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang ((cao hoi) OR (cao hoc)). hieu va phat loc ((va hanh) or (van hanh)) le cuu tre*".