Perhaps you should try some spelling variations:
sach nganh » sach ngan, sach tranh, cac nganh
vu khamh » vu khanh, vu khach, vu thanh
han cong » phan cong, hang cong, hanh cong
cong khi » cong thai, khong khi, co khi
su sach » so sach, vu sach
vu kham » vu khanh
y khi » ly khi, ky khi, my khi

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach nganh y khi đong luc ) OR ( ((vu khamh) OR (vu kham)) han cong khi đong luc ))~.
• Adding a wildcard symbol may retrieve word variants: (( su sach nganh y khi đong luc ) or ( ((vu khamh) or (vu kham)) han cong khi đong luc ))*.