TY - BOOK AU - Ryan,William T. TI - A guide to marketing SN - 0256025762 (pbk.) AV - HF5415 .R9 U1 - 658.8 19 PY - 1981/// CY - Homewood, Ill. PB - Learning Systems Co. KW - Marketing N1 - "An adaptation of material previously published in a programmed learning aid (PLAID) entitled Principles of marketing; Includes index ER -