Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang dau » hang dau, xang dau, nang du
hang de » hoang de, hanh de, hang di
luc van » luoc van, luu van, duc van
xuc van » duc van, vuc van, xuc ban
hieu ve » hieu va, hieu van
dau hoi » cau hoi, dai hoi, dan hoi
ly nang » ky nang, ly hang, ly vang
cua tuc » cua duc, cua tu, cua thuoc
ve cac » va cac, vien cac
de cua » le cua, te cua, dieu cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ly nang dau hoi. hieu ve cac ((xuc van) or (luc van)) hang de cua tuc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ly nang dau hoi. hieu ve cac ((xuc van) OR (luc van)) hang de cua tuc.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ly nang dau hoi. hieu ve cac ((xuc van) or (luc van)) hang de cua tuc".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ly nang dau hoi. hieu ve cac ((xuc van) or (luc van)) hang de cua tuc*.