Perhaps you should try some spelling variations:
khau thong » khau thuong, khap thong, khau tong
sach tren » sach tien, sach tranh
tren thuc » trien thuc, tron thuc, trinh thuc
hanh khoa » anh khoa, hanh hoa, han khoa
hoc thong » hoc thuong, hoc trong, hoc hong
thuc hang » thu hang, phuc hang, thuy hang
hang khoa » dung khoa
khoa khau » khoa kham, khoa phau, khoa chau
khoa hoc » hoa hoc
sach nam » sach nay, sach tham, sach nang
nam thuc » nam thuoc, am thuc, nam thu
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 tren thuc hanh khoa hoc thong ) or ( tu sach nam thuc hang khoa khau thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tren thuc hanh khoa hoc thong ) OR ( tu sach nam thuc hang khoa khau thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach tren thuc hanh khoa hoc thong ) or ( tu sach nam thuc hang khoa khau thong ))*.