Perhaps you should try some spelling variations:
khan thong » khap thong, khau thong, nhan thong
sach tham » sach nha
tham thuc » nham thuc, pham thuc, tam thuc
thuc hang » thuc hanh, thu hang, phuc hang
hang khoa » dung khoa
sach tren » sach tien, sach tranh
tren thi » trien thi, tran thi, trieu thi
kho khan » khoa kham, khoa than
tu sach » thu sach, su sach, te sach
khoa he » hoa he, khoa hoc, khong he
thi tac » thi tam, thi thao, thi tran
tac kho » toc kho, tac cho, cac khoi

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 hang khoa he thong ) or ( tu sach tren thi tac kho khan thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tham thuc hang khoa he thong ) OR ( tu sach tren thi tac kho khan thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach tham thuc hang khoa he thong ) or ( tu sach tren thi tac kho khan thong ))*.