Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
cam thuc » am thuc, nam thuc, cam thu
thi hang » thi hanh, thi hong, thi thanh
vanh dai » van dai, vanh tai, lanh dao
hanh dai » hanh tai, hanh dao, thanh dat
thi nang » thi cong, ki nang, thi hanh
thuc va » thuc vat, thuc dan, thuc day
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
ve cam » ve cham, ve cac, va cam

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 ((thi hang) or (thi nang)) xa hoi. hieu ve cam thuc va ((hanh dai) OR (vanh dai)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((thi hang) OR (thi nang)) xa hoi. hieu ve cam thuc va ((hanh dai) OR (vanh dai)) su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((thi hang) or (thi nang)) xa hoi. hieu ve cam thuc va ((hanh dai) OR (vanh dai)) su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((thi hang) or (thi nang)) xa hoi. hieu ve cam thuc va ((hanh dai) OR (vanh dai)) su triet*.