Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
trang trinh » tra trinh, trang tri, thanh trinh
hang trinh » hanh trinh, thanh trinh, cong trinh
sach trinh » sach tranh, hanh trinh, sach kinh
nghien dau » nghiem dau, nghiep dau, nghien cuu
thiet de » thiet ke, nhiet de, thiet yeu
thu sach » tu sach, thuat sach, thuoc sach
dau hoc » dai hoc, du hoc, dan hoc
de hoc » te hoc, du hoc, dien 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: (( ly ((hang trinh) OR (trang trinh)) thiet de hoc ) OR ( thu sach trinh nghien dau hoc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ly ((hang trinh) OR (trang trinh)) thiet de hoc ) or ( thu sach trinh nghien dau hoc ))~".
• Adding a wildcard symbol may retrieve word variants: (( ly ((hang trinh) OR (trang trinh)) thiet de hoc ) or ( thu sach trinh nghien dau hoc ))*.