Perhaps you should try some spelling variations:
ngan cong » nganh cong, nganh nong, ngan hang
anh ngan » anh nhan, nhanh ngan, doanh ngan
cong khi » cong thai, khong khi, co khi
nha khoa » nhi khoa, da khoa, bia khoa
nhan hoa » nhan khoa, phan hoa, thanh hoa
su sach » so sach, vu sach
so anh » so sanh, so danh, do anh

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( so anh ngan cong khi đong luc ) or ( su sach ((nha khoa) or (nhan hoa)) khi đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so anh ngan cong khi đong luc ) OR ( su sach ((nha khoa) OR (nhan hoa)) khi đong luc )).
• Adding a wildcard symbol may retrieve word variants: (( so anh ngan cong khi đong luc ) or ( su sach ((nha khoa) or (nhan hoa)) khi đong luc ))*.