Perhaps you should try some spelling variations:
nghien thu » nghiem thuc, nghiep thuc, nghien cuu
cach thuc » anh thuc, cac thu
toc cach » hoc cach, toc sach, truoc cach
cong coc » cong cuoc, cong cac, cong co
coc hang » hoc hang, oc hang, moc hoang
hang hoa » hang khoa, thanh hoa, hang va
nhan van » nhan dan, nhan va, phan van
va nhan » van nhan, ca nhan, va phan

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "toc cach thuc vat, nghien thu cong coc hang hoa ((hoc xa) OR (hoc ma)) hoi va nhan van~".
• Adding a wildcard symbol may retrieve word variants: toc cach thuc vat, nghien thu cong coc hang hoa ((hoc xa) OR (hoc ma)) hoi va nhan van*.