Perhaps you should try some spelling variations:
tranh nhiem » trach nhiem, trinh nhiet
nghiem quoc » nghiem duoc, nghiem nuoc, nghiem thuoc
nghiep quoc » nghiep cuoc, nghiep quan, nghiem duoc
sach tranh » canh tranh
nhiem duoc » nghiem duoc, hiem duoc, nhiem cuoc
sach tren » sach tien
duoc hoc » quoc hoi
su sach » so sach, vu sach
tu sach » thu sach, te sach, tu cach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( su sach tranh nhiem duoc hoc ) or ( tu sach tren ((nghiem quoc) OR (nghiep quoc)) hoi ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach tranh nhiem duoc hoc ) OR ( tu sach tren ((nghiem quoc) OR (nghiep quoc)) hoi )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su sach tranh nhiem duoc hoc ) or ( tu sach tren ((nghiem quoc) OR (nghiep quoc)) hoi ))".
• Adding a wildcard symbol may retrieve word variants: (( su sach tranh nhiem duoc hoc ) or ( tu sach tren ((nghiem quoc) OR (nghiep quoc)) hoi ))*.