Perhaps you should try some spelling variations:
sach trinh » sach tranh, sach kinh, sac tinh
hanh trinh » canh tranh, hanh chinh
sach tren » sach tien, sach tranh
trinh thi » trinh tai, dinh thi, trinh tu
thi duoc » chi duoc, thi nuoc, thi quoc
duoc hoc » quoc hoi
nghe di » nghe vi, nghe dien, nghe dan
tu hanh » du hanh, lu hanh, thuc hanh
di hoc » dai hoc, dia hoc, li hoc

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

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