Perhaps you should try some spelling variations:
hieu hieu » hien hieu, hieu hien, thien hieu
toc sach » hoc sach, doc sach, thuoc sach
hieu cac » hieu luc, hieu va, hieu van
tu sach » thu sach, su sach, te sach
nam dao » nam dan, nam sao, nam cao
xuc nam » duc nam, xuc cam, cuc nam
cac xuc » cam xuc, cac nuoc, chat xuc
mai hoi » mai khoi, dai hoi, lai hoi
cu tren » tu tren, dua tren
ma hoi » xa hoi, ma hoa, me hoi
dao va » dao van, tao va, do va
va cu » va cau, va chu, va su

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (toc sach)) ky nang ((ma hoi) OR (mai hoi)). hieu hieu cac xuc nam dao va cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (toc sach)) ky nang ((ma hoi) OR (mai hoi)). hieu hieu cac xuc nam dao va cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (toc sach)) ky nang ((ma hoi) OR (mai hoi)). hieu hieu cac xuc nam dao va cu tren".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (toc sach)) ky nang ((ma hoi) OR (mai hoi)). hieu hieu cac xuc nam dao va cu tren*.