Amazon has them! $16.40

Ampad Computation Book, 4x4 Quad Ruled, 76 Sheets, Ivory, 11-3/4" x 9-1/4", 1 per Pack (22-157) https://www.amazon.com/dp/B000DZEA2G/ref=cm_sw_r_cp_api_glt_fabc_TAZ74Y35AB5960S7FJAW