Perhaps you should try some spelling variations:
nang khoa » hang khoa, dang khoa, nang hoa
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
khoa hoc » hoa hoc
hanh di » hanh vi, hanh de, hang di
duc ban » duc van, dua ban, duc man
hieu ve » hieu va, hieu van
ty nang » ky nang, ty xang, ty hang
cua cau » cua cac, cua chu, cua cay
ve cac » va cac, vien cac
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: ((toc sach) OR (hoc sach)) ty nang khoa hoc. hieu ve cac ((duc ban) or (duc tan)) hanh di cua cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ty nang khoa hoc. hieu ve cac ((duc ban) OR (duc tan)) hanh di cua cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (hoc sach)) ty nang khoa hoc. hieu ve cac ((duc ban) or (duc tan)) hanh di cua cau*".