Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
van hanh » van thanh, ban hanh, van anh
thi hang » thi hanh, thi nang, thi hong
cac xuc » cam xuc, cac nuoc, chat xuc
hanh di » hanh vi, hanh de, hang di
xuc van » duc van, luc van, vuc van
hieu ve » hieu va, hieu van
cho hoc » co hoc, khoa hoc
ty hang » ly hang, ty xang, thu hang
ve cac » va cac, vien cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ((ty hang) or (thi hang)) cho hoc. hieu ve cac xuc van hanh di ((cua cay) OR (cua cac))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ((ty hang) OR (thi hang)) cho hoc. hieu ve cac xuc van hanh di ((cua cay) OR (cua cac))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ((ty hang) or (thi hang)) cho hoc. hieu ve cac xuc van hanh di ((cua cay) OR (cua cac))*".