Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
hieu van » hieu va, thien van, lieu va
van pham » san pham, van phan, van phat
viet cua » viec cua, biet cua, nhiet cua
viet qua » vien quan, ket qua, viet ha
doc sac » doc sach, dac sac, hoc sach
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
viet ca » viet ha, viet co, viet a
sac ky » cac ky, sai ky
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: doc sac ky nang x hoi. hieu van pham thuc va danh ((((viet cua) or (viet ca))) or (viet qua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sac ky nang x hoi. hieu van pham thuc va danh ((((viet cua) OR (viet ca))) OR (viet qua)) tre.
• Adding a wildcard symbol may retrieve word variants: doc sac ky nang x hoi. hieu van pham thuc va danh ((((viet cua) or (viet ca))) or (viet qua)) tre*.