Perhaps you should try some spelling variations:
dang cay » dang xay, dang ca, dang cac
lang phi » lang phu, lang chai, lang ha
su sach » so sach, vu sach
duc ban » duc van, dua ban, duc man
cua tre » cuu tre, cua triet, dua tren
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cay cho » cap cho, cao cho, cay co
ky dang » ky nang, ky danh
ve cao » va cao, ve bao, ve cac
cua te » cua tu

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 dang cay cho. hieu ve cao ((duc ban) OR (duc tan)) lang phi ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky dang cay cho. hieu ve cao ((duc ban) OR (duc tan)) lang phi ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky dang cay cho. hieu ve cao ((duc ban) OR (duc tan)) lang phi ((cua tre) or (cua te))".
• Adding a wildcard symbol may retrieve word variants: su sach ky dang cay cho. hieu ve cao ((duc ban) OR (duc tan)) lang phi ((cua tre) or (cua te))*.