Perhaps you should try some spelling variations:
trien khai » trien nha
sach trien » sach tien, sach tren, sach thieu
doc sach » toc sach, nuoc sach, dac sac
hoc sach » hoc sinh, hoc cac, hoc anh
nha chai » nhan chan, nhan chat, nha cao
chai hoa » chai khoa, chat hoa, cai hoa
khai hoa » khai hoan, hai hoa, kha hoa
tu sach » thu sach, su sach, te sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( ((doc sach) OR (hoc sach)) nha chai hoa hoc ) or ( tu sach trien khai hoa hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((doc sach) OR (hoc sach)) nha chai hoa hoc ) OR ( tu sach trien khai hoa hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((doc sach) OR (hoc sach)) nha chai hoa hoc ) or ( tu sach trien khai hoa hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( ((doc sach) OR (hoc sach)) nha chai hoa hoc ) or ( tu sach trien khai hoa hoc ))*.