Perhaps you should try some spelling variations:
dieu tra » dieu tri, kiem tra
va thanh » gia thanh, ban thanh, va tinh
tu sach » thu sach, su sach, te sach
cac luc » cau luc, coc luc, cac nuoc
hieu ve » hieu va, hieu van
tang ma » mang may, tang van
sang ma » nang ma, sang tao, mang may
luc va » duc va, tuc va, loc va
ve cac » va cac, vien cac

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 y ((sang ma) or (tang ma)) hoa. hieu ve cac luc va thanh ((dieu cua) OR (dieu tra)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((sang ma) OR (tang ma)) hoa. hieu ve cac luc va thanh ((dieu cua) OR (dieu tra)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((sang ma) or (tang ma)) hoa. hieu ve cac luc va thanh ((dieu cua) OR (dieu tra)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((sang ma) or (tang ma)) hoa. hieu ve cac luc va thanh ((dieu cua) OR (dieu tra)) tre*.