Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
sach ty » sach y, sach tu, sach thu
hanh di » hanh vi, hanh de, hang di
ve cham » va cham, ve chat, vu cham
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, nang ma
ve cam » ve cac, va cam, ve cai
sai ky » sac ky
di cua » dai cua, doi cua, de cua

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 ty) or (sai ky)) nang xa hoi. hieu ((ve cam) OR (ve cham)) thuc van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sai ky)) nang xa hoi. hieu ((ve cam) OR (ve cham)) thuc van hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) or (sai ky)) nang xa hoi. hieu ((ve cam) OR (ve cham)) thuc van hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sai ky)) nang xa hoi. hieu ((ve cam) OR (ve cham)) thuc van hanh di cua tre*.