Perhaps you should try some spelling variations:
phau thong » phap thong, khau thong, phan thong
khoa phau » hoa phan, khoa kham, khoa than
cach khoa » bach khoa, cac khoa, cac khoan
dai khoa » da khoa, tai khoa, dac khoa
sach dao » lanh dao
tu sach » thu sach, su sach, te sach
so sach » bo sach, co sach, hoc sach
ve cach » va cach, ve cac, ve canh
so sanh » do sanh
khoa he » hoa he, khoa hoc, khong he
tri ve » tri va, tri le, trinh ve
dao le » do le, dao ve, hao le
le dai » ly dai, li dai, le dan

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( ((so sach) or (so sanh)) tri ve cach khoa phau thong ) or ( tu sach dao le dai khoa he thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((so sach) OR (so sanh)) tri ve cach khoa phau thong ) OR ( tu sach dao le dai khoa he thong )).
• Adding a wildcard symbol may retrieve word variants: (( ((so sach) or (so sanh)) tri ve cach khoa phau thong ) or ( tu sach dao le dai khoa he thong ))*.