Perhaps you should try some spelling variations:
khoan phan » khoan phai, khoan thanh, hoa phan
phan thong » phan thuong, phan hong, phan tong
tri truoc » tri thuoc, tri thuc, gi truoc
truoc cac » truoc cach, truoc cang, truoc cuoc
hoach thi » hoach thu, hoach toi, hoach thay
hanh khoa » hang khoa, anh khoa, hanh hoa
hoc thong » hoc thuong, hoc trong, hoc hong
sach tri » sach tai, sach tren, sach truc
thi hanh » thi thanh
khoa hoc » hoa hoc
so sach » so sanh, bo sach, co sach
thi thi » thi thai, thi thin, thi thu

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( so sach tri truoc cac khoan phan thong ) or ( thu hoach thi thi hanh khoa hoc thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so sach tri truoc cac khoan phan thong ) OR ( thu hoach thi thi hanh khoa hoc thong )).
• Adding a wildcard symbol may retrieve word variants: (( so sach tri truoc cac khoan phan thong ) or ( thu hoach thi thi hanh khoa hoc thong ))*.