Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
tu sach » thu sach, su sach, te sach
ty nang » ky nang, ty hang, ly nang
hieu ve » hieu va, hieu van
ve tham » va tham, ve cham, vi tham
thuc xa » thuc xay, tuc xa, thuc va
cua tre » cua te, cuu tre, cua triet

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 ((ty nang) or (ty xang)) xa hoi. hieu ve tham thuc xa ((tinh toan) or (thanh san)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty nang) OR (ty xang)) xa hoi. hieu ve tham thuc xa ((tinh toan) OR (thanh san)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) or (ty xang)) xa hoi. hieu ve tham thuc xa ((tinh toan) or (thanh san)) cua tre*.