Perhaps you should try some spelling variations:
nhan tai » hang tai, van tai, toan tai
toc sach » hoc sach, doc sach, thuoc sach
tam thuc » tham thuc, am thuc, nam thuc
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
va nhan » van nhan, ca nhan, va phan
thuc va » thuc vat, thuc dan, thuc day
nang ma » tang ma, sang ma, nang cao
va tam » van tam, va tham, va tac
cuc te » cua te, cuc thue, cuc tieu

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) or (toc sach)) ky ((nang x) or (nang ma)) hoi. hieu va tam thuc va nhan tai cuc te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (toc sach)) ky ((nang x) OR (nang ma)) hoi. hieu va tam thuc va nhan tai cuc te.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (toc sach)) ky ((nang x) or (nang ma)) hoi. hieu va tam thuc va nhan tai cuc te*.