Perhaps you should try some spelling variations:
chat truc » cau truc, chat xuc
thu sach » tu sach, thuat sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
cau tren » cu tren, dau tren, ca tren
cho hoc » co hoc, khoa hoc
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
va hanh » va thanh, va danh, ban hanh
cao hoc » co hoc, chat hoc
va chat » van chat, va phat, cao chat
ve cau » ke cau, va cau, ve cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang ((cao hoc) or (cho hoc)). hieu va chat truc ((va hanh) OR (van hanh)) ve cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ((cao hoc) OR (cho hoc)). hieu va chat truc ((va hanh) OR (van hanh)) ve cau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ((cao hoc) or (cho hoc)). hieu va chat truc ((va hanh) OR (van hanh)) ve cau tren*".