Perhaps you should try some spelling variations:
sach trien » sach tien, sach tren, sach thieu
trien thuc » trien thuoc, tren thuc, trien thuat
khan thong » khap thong, khau thong, nhan thong
pho thong » he thong
hanh kho » hanh khu, hang khoa, hanh theo
kho khan » khoa kham, khoa than
thu sach » tu sach, thuat sach, thuoc sach
sach thu » sach thue, sach thieu, sach tham
cac khoi » cac thoi, cac khoan, cach thoi
khoi pho » khoi tho, khoi khoa, hoc pho
su sach » so sach, vu sach
thu phu » thuc phu, thi phu, khu phu
phu cac » phuc cac, pha cac, phu can

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( su sach trien thuc hanh kho khan thong ) or ( thu sach thu phu cac khoi pho thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach trien thuc hanh kho khan thong ) OR ( thu sach thu phu cac khoi pho thong )).
• Adding a wildcard symbol may retrieve word variants: (( su sach trien thuc hanh kho khan thong ) or ( thu sach thu phu cac khoi pho thong ))*.