Perhaps you should try some spelling variations:
sach ngon » danh ngon, canh ngon, gach ngoi
sach ngan » sach nha, sach han, sach nang
vu sach » vu bach, su sach, vu khach
doc khi » doi khi, hoc khoi, dong khi
hoc khi » hoc khoi, hoc khia, hoc ki
ngan ky » nganh ky, nhan ky, ngan hay
ky khi » ky thi, ly khi

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( vu sach ngon ((doc khi) or (hoc khi)) đong luc ) or ( vu sach ngan ky khi đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( vu sach ngon ((doc khi) OR (hoc khi)) đong luc ) OR ( vu sach ngan ky khi đong luc )).
• Adding a wildcard symbol may retrieve word variants: (( vu sach ngon ((doc khi) or (hoc khi)) đong luc ) or ( vu sach ngan ky khi đong luc ))*.