Walker's, Building Estimator's Reference Book, 29th EditionWalkers Building Estimators Reference Book is the single most important resource you can own. It gives you the tools you need to work up your own costs per job. With Walkers, you get material quantities and labor productivity for your job based on your job conditions thats the kind of flexibility and reliability no computer program or unit price catalog can provide. For accurate building costs, turn to the source that construction professionals have