專注，是一種資產：七件事練習法，打造富足的精神資本 (二手書交易資訊)

[{"sale_price":202,"disc":"63","prod_count":1,"sale_month":"202001","avg_price":202,"avg_disc":63},{"sale_price":468,"disc":146,"prod_count":2,"sale_month":"202002","avg_price":234,"avg_disc":73},{"sale_price":642,"disc":200,"prod_count":3,"sale_month":"202003","avg_price":214,"avg_disc":67}]