Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
nang mai » nang ma, nang tai, lang mai
te sach » toc sach
hieu va » lieu va, hieu qua
danh vi » hanh vi, dinh vi, danh di
va danh » va dinh, va dan, va hanh
cac hoc » cach hoc, cac hop, bac hoc
hieu ve » hieu van
mai hoi » mai khoi, dai hoi, lai hoi
vi cua » vai cua, di cua
cua te » cua tu

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 (thuat sach)) ky nang mai hoi. ((hieu ve) OR (hieu va)) cac hoc va danh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (thuat sach)) ky nang mai hoi. ((hieu ve) OR (hieu va)) cac hoc va danh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (thuat sach)) ky nang mai hoi. ((hieu ve) OR (hieu va)) cac hoc va danh vi cua te".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (thuat sach)) ky nang mai hoi. ((hieu ve) OR (hieu va)) cac hoc va danh vi cua te*.