Perhaps you should try some spelling variations:
thieu nghiem » thu nghiem, thieu nhi, thuc nghiem
tham nghiem » trac nghiem, thuc nghiem, thu nghiem
thi nghiem » thuc nghiem
thu sach » tu sach, thuat sach, thuoc sach
nghiem d » nghiem de, nghiem do, nghiem _
te sach » toc sach
d hoc » du hoc, ad hoc, de hoc

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: (( te sach ((tham nghiem) OR (thi nghiem)) hoa hoc ) OR ( thu sach thieu nghiem d hoc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( te sach ((tham nghiem) OR (thi nghiem)) hoa hoc ) or ( thu sach thieu nghiem d hoc ))~".
• Adding a wildcard symbol may retrieve word variants: (( te sach ((tham nghiem) OR (thi nghiem)) hoa hoc ) or ( thu sach thieu nghiem d hoc ))*.