Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
cham thuc » nham thuc, tham thuc, pham thuoc
thu sach » tu sach, thuat sach, thuoc sach
hang cao » hoang cao, nang cao, hang ca
sach ty » sach y, sach tu, sach thu
ty hang » ly hang, ty xang, thi hang
cao hoi » cau hoi, co hoi, cao hoc
hieu vu » hieu va, hieu ve, hieu su
dan vai » dan va, dan tai, dan vat
va dan » ca dan, va dao, va dau
vai va » mai va, dai va, hai va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ty hang cao hoi. hieu vu ((cham thuc) OR (pham thuc)) va dan vai va thiet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty hang cao hoi. hieu vu ((cham thuc) OR (pham thuc)) va dan vai va thiet".
• Adding a wildcard symbol may retrieve word variants: thu sach ty hang cao hoi. hieu vu ((cham thuc) OR (pham thuc)) va dan vai va thiet*.