Perhaps you should try some spelling variations:
doanh khoa » toan khoa
tieu doanh » tieu danh, trien doanh, dieu danh
sach tren » sach tien, sach tranh
tren tuan » tran tuan, trung tuan, tren trang
tuan bang » tuan dang, tuan hoang, thuat bang
phuong he » phuong te, phuong de, phuong ke
hoach bai » hoach bang, hoc bai, sach bai
hoc trong » hoc thuong, hoc tieng, dot trong
bai tieu » ai tieu, dai tieu, tai tieu
khoa hoc » hoa hoc
tu sach » thu sach, su sach, te sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu sach tren tuan bang phuong he thong ) or ( thu hoach bai tieu doanh khoa hoc trong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tren tuan bang phuong he thong ) OR ( thu hoach bai tieu doanh khoa hoc trong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach tren tuan bang phuong he thong ) or ( thu hoach bai tieu doanh khoa hoc trong ))*.