Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
khau thong » khau thuong, khap thong, khau tong
phan thong » phan thuong, phan hong, phan tong
tac thuoc » tao thuoc, truc thuoc, tac thuong
toan thai » toan tai, toan phai, hoang thai
thai tich » thai tinh, thai lich, than tich
khoa phan » hoa phan, khoa than, khoa phau
sang tac » sang tao, sang tai, sang than
nha khau » nhap khau, nha kham, nha khach
tap toan » tap doan, tap quan, bai toan
tich cac » tich va, tich bao
cac khoa » cac khoan, cac khoi, dac khoa
tu sang » thu sang, tu san, tu lang

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu sang tac thuoc sach nha khau thong ) or ( tap toan thai tich cac khoa phan thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sang tac thuoc sach nha khau thong ) OR ( tap toan thai tich cac khoa phan thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sang tac thuoc sach nha khau thong ) or ( tap toan thai tich cac khoa phan thong ))*.