Perhaps you should try some spelling variations:
nghien cac » nghiep cach, nghien cuu, nghiep cay
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
cac cong » cua cong
cong coc » cong cuoc, cong cac, cong co
coc phan » co phan, hoc phan, cac phan
phan hoa » phan loai, phan phoi, phan hong
nang dan » nang danh, nong dan, nang dau
dao tai » dao thai, dao tao, cao tai
hoc mai » hoc ma, hoc dai, hoc bai
mai hoi » mai khoi, dai hoi, lai hoi
chuc » thuc, chu, chua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) OR (hoc sach)) dao tai, nghien cac cong coc phan hoa hoc mai hoi chuc nang dan~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (hoc sach)) dao tai, nghien cac cong coc phan hoa hoc mai hoi chuc nang dan".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (hoc sach)) dao tai, nghien cac cong coc phan hoa hoc mai hoi chuc nang dan*.