Perhaps you should try some spelling variations:
khau thong » khau thuong, khap thong, khau tong
phan thong » phan thuong, phan hong, phan tong
thuc cach » thuoc sach, truoc cach, thuc hanh
cach khoa » bach khoa, cac khoa, cac khoan
sach tai » sach bai, sach tham, sach dao
tai thuc » thai thuc, tri thuc, dai thuc
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 tai thuc cach khoa ((khau thong) or (phan thong))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tai thuc cach khoa ((khau thong) OR (phan thong)).
• Adding a wildcard symbol may retrieve word variants: tu sach tai thuc cach khoa ((khau thong) or (phan thong))*.