Perhaps you should try some spelling variations:
thieu nghiem » thi nghiem, thu nghiem, thieu nhi
nghiem duoc » nghiem thuoc, nghe duoc
sach trinh » hanh trinh, sach kinh, sach tren
sach tranh » canh tranh
duoc hoc » quoc hoi
nghien d » nghiem d, nghien o, nghiem de
su sach » so sach, vu sach
d hoc » du hoc, ad hoc, de hoc

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 thieu nghiem duoc hoc ) or ( vu ((sach trinh) OR (sach tranh)) nghien d hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach thieu nghiem duoc hoc ) OR ( vu ((sach trinh) OR (sach tranh)) nghien d hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su sach thieu nghiem duoc hoc ) or ( vu ((sach trinh) OR (sach tranh)) nghien d hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( su sach thieu nghiem duoc hoc ) or ( vu ((sach trinh) OR (sach tranh)) nghien d hoc ))*.