shuāng bǎi fāng zhēn
refers to 百花運動|百花运动[Bai3 hua1 Yun4 dong4] with its slogan 百花齊放,百家爭鳴|百花齐放,百家争鸣
双
shuāng
two
百
bǎi
hundred
方
fāng
square
针
zhēn
variant of 針|针[zhen1], needle