Perhaps you should try some spelling variations:
sach nuoc » sach duoc, cac nuoc, bach tuoc
thu nang » thi nang, thu hang, thu bang
hieu van » hieu va, thien van, lieu va
bac nuoc » cac nuoc, bach tuoc, hoc nuoc
sach thu » sach thue, sach thieu, sach tham
man tinh » ban tinh, quan tinh, doan tinh
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
hai cua » thai cua, dai cua, hoi cua
cua te » cua tu

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 thu nang xa hoi. hieu van ((bac nuoc) OR (sach nuoc)) ((man tinh) or (may tinh)) hai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thu nang xa hoi. hieu van ((bac nuoc) OR (sach nuoc)) ((man tinh) OR (may tinh)) hai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thu nang xa hoi. hieu van ((bac nuoc) OR (sach nuoc)) ((man tinh) or (may tinh)) hai cua te".
• Adding a wildcard symbol may retrieve word variants: tu sach thu nang xa hoi. hieu van ((bac nuoc) OR (sach nuoc)) ((man tinh) or (may tinh)) hai cua te*.