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
sach thu » sach thue, sach thieu, sach tham
thu thuc » thuc thuc, thu thuoc, thue thuc
thuc cac » thuc cach, tuc cac, phuc cac
cac khoi » cac thoi, cac khoan, cach thoi
khoi pho » khoi tho, khoi khoa, hoc pho
te sach » toc sach
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 trien thuc hanh kho khan thong ) or ( tu sach thu thuc cac khoi pho thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( te sach trien thuc hanh kho khan thong ) OR ( tu sach thu thuc cac khoi pho thong )).
• Adding a wildcard symbol may retrieve word variants: (( te sach trien thuc hanh kho khan thong ) or ( tu sach thu thuc cac khoi pho thong ))*.