Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
vien cac » vien bach, vien dai, vien da
van hanh » van thanh, ban hanh, van anh
hanh di » hanh vi, hanh de, hang di
vuc van » duc van, luc van, thuc van
cua cau » cua cac, cua chu, cua cay
cho hoc » co hoc, khoa hoc
ty hang » ly hang, thi hang, thu hang
di cua » dai cua, doi cua, de cua
ve cac » va cac

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

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