DURABLE GOODS by Elizabeth Berg (Avon: $9.; 192 pp.). Berg’s brief novel describes a girl’s coming of age during a sweltering summer in Texas. Poised on the brink of adolescence, Katie realizes she is no longer child, but not yet woman. She has no one to talk to about her shifting identity: Her mother recently died of cancer; her older sister only wants to escape their remote, abusive father. Katie communes with her mother’s spirit and writes poetry, as she longs for a better, kinder adulthood.