Perhaps you should try some spelling variations:
tranh nghiem » trac nghiem, trach nhiem, trinh nghien
sanh tranh » canh tranh, sach tranh, lanh tranh
nghiem ye » nghiem de, nghiem te, nghiem ve
sach trac » sach truc, sach tranh, sach tren
sach tham » sach nha
nghiem ad » nghiem d, nghiem ban, nghiem lam
so sanh » do sanh
ye hoc » y hoc, te 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: (( so sanh tranh nghiem ye hoc ) or ( co ((sach trac) OR (sach tham)) nghiem ad hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so sanh tranh nghiem ye hoc ) OR ( co ((sach trac) OR (sach tham)) nghiem ad hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( so sanh tranh nghiem ye hoc ) or ( co ((sach trac) OR (sach tham)) nghiem ad hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( so sanh tranh nghiem ye hoc ) or ( co ((sach trac) OR (sach tham)) nghiem ad hoc ))*.