Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
dang mau » dong mau, dang van, dang su
hieu va » lieu va, hieu qua
hanh ki » hanh vi, hanh ky, hanh kien
va tham » van tham, va cham, va thanh
tu sach » thu sach, su sach, te sach
sach vu » sach va, sach tu, sach uu
dang ma » dang mam, dang mat, tang ma
su tien » su kien, su hien, tu tieng
ki su » ky su

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 vu ((dang ma) or (dang mau)) hoi. hieu va tham thuc van hanh ki su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach vu ((dang ma) OR (dang mau)) hoi. hieu va tham thuc van hanh ki su tien.
• Adding a wildcard symbol may retrieve word variants: tu sach vu ((dang ma) or (dang mau)) hoi. hieu va tham thuc van hanh ki su tien*.