Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
huong doi » huong dan, trong doi, dung doi
sat huong » suat huong, san huong, sat muong
thuc sat » thuc vat, thuc san, thuc hoat
cau tren » cu tren, dau tren, ca tren
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau treo
su sach » so sach, vu sach
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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 ky nang ((x hoi) or (o hoi)). hieu ve pham thuc sat huong doi ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((x hoi) OR (o hoi)). hieu ve pham thuc sat huong doi ((cuu tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang ((x hoi) or (o hoi)). hieu ve pham thuc sat huong doi ((cuu tre) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((x hoi) or (o hoi)). hieu ve pham thuc sat huong doi ((cuu tre) OR (cau tren))*.