Perhaps you should try some spelling variations:
tran thong » toan thong, tran hong, tran trong
sach tham » sach nha
tham thuc » nham thuc, pham thuc, tam thuc
thuc cach » thuoc sach, truoc cach, thuc hanh
khan tong » han tong, phan tong, khau tong
hanh khoa » hang khoa, anh khoa, hanh hoa
khoa tran » khoa than, khoa trung, thoan tran
cach kho » bach khoa, cach thoi, cach pha
kho khan » khoa kham, khoa than
sach tri » sach tai, sach tren, sach truc
tue hanh » tu hanh, tuc hanh, tue anh
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 tham thuc cach kho khan tong ) or ( tu sach tri tue hanh khoa tran thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tham thuc cach kho khan tong ) OR ( tu sach tri tue hanh khoa tran thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach tham thuc cach kho khan tong ) or ( tu sach tri tue hanh khoa tran thong ))*.