Perhaps you should try some spelling variations:
doc thuc » hoc thuc, do thuc, hoc thuoc
coc tuc » coc luc, hoc thuc, hoc truc
tinh va » tich va, trinh van, trinh vat
va tinh » may tinh
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
va cua » va chua, via cua, ca cua
sac ky » cac ky, sai ky
cua te » cua tu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sac ky) OR (sach y)) lang xa hoi. hieu va ((coc tuc) OR (doc thuc)) va tinh va cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sac ky) or (sach y)) lang xa hoi. hieu va ((coc tuc) OR (doc thuc)) va tinh va cua te~".
• Adding a wildcard symbol may retrieve word variants: su ((sac ky) or (sach y)) lang xa hoi. hieu va ((coc tuc) OR (doc thuc)) va tinh va cua te*.