Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
hanh vii » hanh voi, hanh va, hanh noi
tu sach » thu sach, su sach, te sach
thuc xa » thuc xay, tuc xa, thuc va
ve tham » va tham, ve cham, vi tham
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
dai hoi » dai hoc, dai hai, dai moi
mai hoi » mai khoi, lai hoi, mai doi
ty danh » ty doanh, ty anh, ky danh
cu tren » tu tren, dua tren

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 danh ((mai hoi) or (dai hoi)). hieu ve tham thuc xa ((hanh vii) or (hanh vi)) cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty danh ((mai hoi) OR (dai hoi)). hieu ve tham thuc xa ((hanh vii) OR (hanh vi)) cu tren.
• Adding a wildcard symbol may retrieve word variants: tu sach ty danh ((mai hoi) or (dai hoi)). hieu ve tham thuc xa ((hanh vii) or (hanh vi)) cu tren*.