197KiB, 1000x1545, 71Stw4kQHlL.jpg View SameGoogleiqdbSauceNAO Anonymous Thu 13 May 06:50:14 2021 No.13123238 ViewReplyOriginalReport Quoted By: >>13123253 >>13123276 >>13123356 >>13123524 >>13123560 What's the /sci/ approved book , or a good book on learning problem solving in Mathematics ?