Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
thuc xay » thuc day, tuc xay, thuat xay
tu sach » thu sach, te sach, tu cach
han tai » hang tai, nhan tai, van tai
xay han » xay chen, bay than, cay than
su pham » san pham
hieu su » hieu sau, tieu su, hieu so
nang xa » nang x, lang xa, nang ma
su sach » so sach, vu sach
cua tu » cua tuc, cua cu, cua te
cua su » qua 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) or (su sach)) ky nang xa hoi. hieu su pham thuc xay han tai ((cua tu) OR (cua su))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang xa hoi. hieu su pham thuc xay han tai ((cua tu) OR (cua su)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang xa hoi. hieu su pham thuc xay han tai ((cua tu) OR (cua su))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang xa hoi. hieu su pham thuc xay han tai ((cua tu) OR (cua su))*.