Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nam thuc, nham thu
cham thuc » pham thuc, tham thuc, pham thuoc
dac nhan » cac nhan, danh nhan, ca nhan
day hanh » day nhanh, day thanh, dao hanh
sach ty » sach y, sach tu, sach thu
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
te cua » tue cua, le cua, de cua
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty nang x hoi. hieu ve ((cham thuc) OR (nham thuc)) ((day hanh) or (dac nhan)) te cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang x hoi. hieu ve ((cham thuc) OR (nham thuc)) ((day hanh) OR (dac nhan)) te cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty nang x hoi. hieu ve ((cham thuc) OR (nham thuc)) ((day hanh) or (dac nhan)) te cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty nang x hoi. hieu ve ((cham thuc) OR (nham thuc)) ((day hanh) or (dac nhan)) te cua tre*.