Perhaps you should try some spelling variations:
toan cau » toan cao, toan ban, toan tap
quan cau » quang cao, quan ha, quan cua
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
truc va » thuc va, thuc vat, trung va
sach ky » sac ky, sach y, sach ty
su sach » so sach, vu sach
lang ha » long ha
lang xa » dang xay, lang van
cu tren » tu tren, dua tren
va cu » va cau, va chu, va su

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((lang xa) OR (lang ha)) hoi. hieu ((quan cau) or (toan cau)) truc va hanh va cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((lang xa) OR (lang ha)) hoi. hieu ((quan cau) OR (toan cau)) truc va hanh va cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((lang xa) OR (lang ha)) hoi. hieu ((quan cau) or (toan cau)) truc va hanh va cu tren".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((lang xa) OR (lang ha)) hoi. hieu ((quan cau) or (toan cau)) truc va hanh va cu tren*.