Perhaps you should try some spelling variations:
nghiem thuoc » nghiem duoc, nghiem hoa, nghi thuc
sach trinh » sach tranh, hanh trinh, sach kinh
nghiem ban » nghiem van, nghiem xuan, nghiep bang
thuoc nhom » thuoc ho
nghien du » nghiep du, nghien cuu, nghiem dau
cach trac » cach thuc, anh trac, cach ta
su sach » so sach, vu sach
tu cach » tu cac

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 trinh ((nghien du) OR (nghiem ban)) hoc ) OR ( tu cach trac nghiem thuoc nhom ))~.
• Adding a wildcard symbol may retrieve word variants: (( su sach trinh ((nghien du) or (nghiem ban)) hoc ) or ( tu cach trac nghiem thuoc nhom ))*.