God Knows, by Joseph Heller (Dell, $4.50). The life of David, king of Israel, slayer of Goliath, husband of Bathsheba and psalmist without equal, told in modern and very irreverent language by the author of Catch- 22: "Moses has the Ten Commandments, it's true, but I've got much better lines . . ."

Northanger Abbey, by Jane Austen (Bantam, $2.50). Today teen-age girls hit the boards at Ocean City. In the 18th century, young English ladies took the waters at Bath. The object was the same -- to meet eligible and interesting young men. This, one of Jane Austen's early novels, is her most light-hearted, her most obviously satiric, in which she looks not only at social convention but pokes a bit of fun at the gothic romances of her day. Her heroine, Catherine Morland fancies herself a heroine of sch novels, and the consequences of such fantasizing are humorous indeed.

Tales from a Troubled Land, and Too Late the Phalarope, both by Alan Paton (Scribner's, $7.95 and $4.50 respectively). Alan Paton has watched the agony of his country for 82 years, writing about it eloquently in both fiction and autobiography. The first of these books, a collection of 10 short stories, looks at the injustice of racial oppression in South Africa from various angles. The second is a heart-breaking story of a police officer who transgresses his country's most stringent racial laws. NONFICTION

Walking Tours of Old Washington and Alexandria, by Paul Hogarth (EPM Publications, McLean, Va., $24.95). Charming ink and color wash illustrations of Washington area landmarks make this book more than an ordinary guidebook. Paul Hogarth, an Englishman, who has done similar books on Philadelphia and Boston, captures not just the line of Washington architecture but the light and hue of buildings like the Capitol, Anderson House, the Eastern Market, and Georgetown's Old Stone House. There are seven tours suggested, including one of Old Town Alexandria and another of Mount Vernon. Maps are provided.

Son of the Morning Star: Custer and the Little Bighorn, by Evan S. Connell (Perennial/Harper & Row, $8.95). On June 25, 1876, the U.S. 7th Cavalry, guidons fluttering, rode into legend under the command of Brevet Maj. Gen. George Armstrong Custer. This is the story of Custer's downfall and his regiment's massacre, laboriously built up out of thousands of discrete facts and hauntingly told by a master of narrative: ". . . this hotspur refuses to die. He stands forever on that dusty Montana slope."

Somme, by Lyn Macdonald (Salem House, $12.95). At the end of June 1916 the finest British army ever fielded attacked the Germans north of the Somme River in Picardy. After months of fighting and a gain of a hundred yards, after 250,000 died (60,000 on the first day), the British settled down to a long, bloody war of attrition. This painstakingly detailed account of the battle is told in the poignant words of the common soldiers who fought it, and illustrated by absolutely haunting photographs showing how the French farm country today is still scarred from the savage trench warfare of World War I.

Sargazer: Andy Warhol's World and His Films, by Stephen Koch (Marion Boyars, $11.95). In this second edition of a landmark study, Koch brings his subject up to date with a new introductory chapter: "In these latter days, Andy Warhol seems to have recovered -- heaven knows from where -- a look of something almost like health." Written with a most UnWarhol-like energy, Koch analyzes both the Popmaster's cool public image and the voyeuristic artistry of his strange movies. A remarkable and exciting essay.

The North Reports the Civil War and The South Reports the Civil War, by J. Cutler Andrews (University of Pittsburgh Press, $19.95 each). In the American Civil War, As in more recent wars, government and press battled over the right of the press to report war news. Military commanders and civilian officials disagreed: when Henry E. Wing of the New York Tribune refused to show his account of the Battle of the Wilderness to Secretary of War Edwin Stanton, Stanton ordered Wing arrested and shot as a spy. President Lincoln had to intervene to save him. The intrepid reporters of the day had to charter ships, horses and buggies and find telegraph operators to transmit their stories. In these readable volumes, the history of the role journalism played in the great rebellion is engagingly and fully told. The story adds an entirely new dimension to our knowledge of the war.

The Labyrinth of Solitude, by Octavio Paz (Grove, $9.95). Eloquent essays by the Mexican poet and diplomat. Mexico's turbulent history, her poverty and contemporary stuggles to modernize, her historic grudges against Americans are fully and elegantly discussed. Considerable insights are thereby provided for Mexico's ignorant neighbors to the north.

Picking Winners, by Andrew Beyer (Houghton Mifflin, $7.95). The classic book on speed handicapping, by the racing columnist of The Washington Post. See you at the track.

Thinking About the Unthinkable in the 1980s, by Herman Kahn (Touchstone/Simon and Schuster, $8.95). An updating of the nuclear strategist and futurologist's classic 1962 meditation on nuclear war. Kahn, who died in 1983, was unflinching in the unpalatable conclusions that followed from his premise that nuclear weapons will never be disinvented.

Exile: The Unquiet Oblivion of Richard M. Nixon, by Robert Sam Anson (Touchstone/Simon and Schuster, $8.95). Mr. Nixon left the White House in disgrace on Aug. 9, 1974. What he has done with his life since is the subject of Anson's fascinating and thorough report. Book World's reviewer said, "The devil must be given his due, and this is what Anson does. About Richard Nixon there is one inescapable quality; call it resilience or call it courage, but he has it in prodigious supply."

The Last Place on Earth by Roland Huntford (Atheneum, $9.95). This book, reissued in conjunction with an upcoming Masterpiece Theatre series, urges one of the most astonishing reversals in the annals of revisionist history: Robert Falcon Scott, known as a legendarily heroic British explorer, was ignorant, stubborn and incompetent. His faults doomed him and his companions in the 1911 race to be first at the South Pole to certain death. The winner of that race, Norwegian explorer Roald Amundsen, was precisely the sort of fellow Scott should have been in order to succeed: thoughtful, thorough and experienced. The advocate of such an iconoclastic thesis (every schoolboy used to revere Scott as the ultimate noble adventurer) had better command the facts and wield them skillfully. Huntford does both. No one can read this stirring book without at least questioning the standard view of Scott as a hero.

The Mountains of California by John Muir (Penguin, $5.95). Urged by Ralph Waldo Emerson and others, a middle-aged, semi-hermitic nomad finally agreed to stop wandering and write about what he had seen. The result was a series of books written in the late 19th and early 20th century by John Muir, founder of the Sierra Club, which provide incomparable sketches of pristine, untamed America. The present volume serves up the fruits of his journeys in the Golden State, from Mount Shasta to Yosemite. In his introduction Edward Hoagland finds in the book "the feel of an encyclopedic synthesis of experience and observation on a scope and scale Muir had and few outdoorsmen will ever be permitted again."