IMO, you can't go wrong with Anne Watson's Smart Soapmaking, Susan Miller Cavitch's Soapmaker's Companion, or Alicia Grosso's The Everything Soapmaking Book. But just like anything, double check your recipes through a soap calc, because typos can and do happen. Also, Sandy Maine has some nice books, she only uses one soap recipe (crisco, olive and coconut) and the oils are easy to find. And the pictures in her books are lovely.