Perhaps you should try some spelling variations:
sach nganh » sach ngan, sach tranh, cac nganh
nganh khoa » nganh hoa, nganh khong, doanh khoa
khoa kham » kho khan, khoa than
su sach » so sach, vu sach
su cach » tu cach, su cac, cuu cach
pha hoa » phan hoa, pham hoa, phap hoa
hoa khi » hoa phi, hoa hi, hoa thi

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( su sach nganh khoa kham đong luc ) or ( su cach pha hoa khi đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach nganh khoa kham đong luc ) OR ( su cach pha hoa khi đong luc )).
• Adding a wildcard symbol may retrieve word variants: (( su sach nganh khoa kham đong luc ) or ( su cach pha hoa khi đong luc ))*.