Perhaps you should try some spelling variations:
sanh trinh » hanh trinh, anh trinh, sinh trinh
trinh thuc » trinh tu, trinh thi
cach khoan » cac khoan, cach hoan, bach khoa
pho thong » he thong
thuc cach » thuoc sach, truoc cach, thuc hanh
khoan pho » khoan nhoi, khoan phai, khoan hoi
sach tai » sach bai, sach tham, sach dao
cac khoa » cac khoan, cac khoi, dac khoa
khoa pho » khoa phu, khoa khoa, khoa phau
vu sach » vu bach, su sach, vu khach
tai tuc » thai tuc, tai cuc, tai tu
tuc cac » tu cac, tich cac
so sanh » do sanh

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( vu sach tai tuc cac khoa pho thong ) or ( so sanh trinh thuc cach khoan pho thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( vu sach tai tuc cac khoa pho thong ) OR ( so sanh trinh thuc cach khoan pho thong )).
• Adding a wildcard symbol may retrieve word variants: (( vu sach tai tuc cac khoa pho thong ) or ( so sanh trinh thuc cach khoan pho thong ))*.