Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, va tinh
tu sach » thu sach, su sach, te sach
cam duc » cam xuc, cao duc, pham duc
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
thi hai » thi mai, thi hanh
tai hai » dai hai, tai ha, tai phan
vai va » mai va, hai va, lai va
dai va » mai va
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang ((tai hai) OR (thi hai)). hieu ve cam duc va thanh ((vai va) or (dai va)) hieu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((tai hai) OR (thi hai)). hieu ve cam duc va thanh ((vai va) OR (dai va)) hieu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((tai hai) OR (thi hai)). hieu ve cam duc va thanh ((vai va) or (dai va)) hieu".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((tai hai) OR (thi hai)). hieu ve cam duc va thanh ((vai va) or (dai va)) hieu*.