Perhaps you should try some spelling variations:
sach trien » sach tien, sach tren, sach thieu
trien khai » trien nha
khai khoa » thai khoa, chai khoa, khat khoa
sach han » sach tham, sach danh, sach nang
chau hoa » chat hoa, chai khoa, chat khoa
khoa hoc » hoa hoc
te sach » toc sach
cau hoa » cau hoi
tu sach » thu sach, su sach, tu cach

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 han ((chau hoa) OR (cau hoa)) hoc ) or ( tu sach trien khai khoa hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( te sach han ((chau hoa) OR (cau hoa)) hoc ) OR ( tu sach trien khai khoa hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( te sach han ((chau hoa) OR (cau hoa)) hoc ) or ( tu sach trien khai khoa hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( te sach han ((chau hoa) OR (cau hoa)) hoc ) or ( tu sach trien khai khoa hoc ))*.