Perhaps you should try some spelling variations:
nghiem quoc » nghiem nuoc, nghiep quoc, nghiem thuoc
nghiem duoc » nghiem thuoc, nghe duoc
sach tranh » canh tranh
thuoc sach » hoc sach, nuoc sach, thuat sach
nghiem ad » nghiem d, nghiem ban, nghiem lam
can trac » can tac, can tranh, phan trac
tu can » tu ban, tu cac, thu canh

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu can trac nghiem ad hoc ) or ( thuoc sach tranh ((nghiem quoc) or (nghiem duoc)) hoi ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu can trac nghiem ad hoc ) OR ( thuoc sach tranh ((nghiem quoc) OR (nghiem duoc)) hoi )).
• Adding a wildcard symbol may retrieve word variants: (( tu can trac nghiem ad hoc ) or ( thuoc sach tranh ((nghiem quoc) or (nghiem duoc)) hoi ))*.