Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
sach ngan » sach ngon, sach nha, sach han
thu sach » thuoc sach, thu hoach, khau sach
tu sach » su sach, te sach, tu cach
ngan ky » nganh ky, nhan ky, ngan hay
ky khi » ky thi, ly khi
y khi » ly khi, my khi, y chi

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 ngan ky khi đong luc ) or ( ((thu sach) or (thuat sach)) nhah y khi đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach ngan ky khi đong luc ) OR ( ((thu sach) OR (thuat sach)) nhah y khi đong luc )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach ngan ky khi đong luc ) or ( ((thu sach) or (thuat sach)) nhah y khi đong luc ))*.