Perhaps you should try some spelling variations:
tan hanh » tan thanh, tang hanh, toan hanh
sach ky » sac ky, sach y, sach kem
tai cua » thai cua, tai cuc, dai cua
cac duc » cac du, cao duc, cac dac
hieu ve » hieu va, hieu van
nang du » nang tu, nang luc, nang doc
sach ty » sach y, sach tu, sach thu
du hoi » du hoc, lu hoi, di hoi
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: su ((sach ky) or (sach ty)) nang du hoi. hieu ve cac duc tan hanh ((tai cua) or (tri cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) nang du hoi. hieu ve cac duc tan hanh ((tai cua) OR (tri cua)) tre.
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sach ty)) nang du hoi. hieu ve cac duc tan hanh ((tai cua) or (tri cua)) tre*.