Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
va thanh » gia thanh, ban thanh, va tinh
thuc va » thuc vat, thuc dan, thuc day
sach ty » sach y, sach thu, xach tay
hieu vu » hieu va, hieu ve, hieu su
cao hoi » cau hoi, co hoi, cao hoc
sach tu » sach thu, cach tu, sach uu
vu pham » su pham, vi pham, vu kham
va vai » va bai, va van, va dai
va va » va van, va vua, va vat

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 ty) or (sach tu)) nang cao hoi. hieu vu pham thuc va thanh ((va va) or (va vai)) thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach tu)) nang cao hoi. hieu vu pham thuc va thanh ((va va) OR (va vai)) thiet.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sach tu)) nang cao hoi. hieu vu pham thuc va thanh ((va va) or (va vai)) thiet*.