HERE ARE TWO engaging stories from two successful authors whose rooting sections in elementary and intermediate grades should receive these books with ready pleasure.

The Cybil War spins along with discerning perceptions of the relations among three lively characters: Cybil Ackerman, Simon Newton, and his best friend, Tony Angotti. When roles are cast for a school play, the humorous goings-on reveal some passionate antipathies among the characters; a more serious realism enters when Simon's father deserts his family, taking the car and half the money in the bank account.

Cybil, Simon (who has been in love with her for three years) and Tony form a triangle bounded with varying degrees of friendship and love. The deepening of their intense childhood emotions is viewed with the humor we have come to expect of the author of the Newbery Medal-winning The Summer of the Swans and other perceptive stories. With acute verisimilitude, Byars gives us children confronting each other in a preadolescent rage of competition, peppered by epithets chosen with an equally preadolescent level of subtlety. This childishness characterizes their attitudes towards the roles they are offered in the class nutrition play: Simon, who wishes to be Mr. Indigestion, loses that part when Cybil convinces her classmates (mostly girls) that they should have a Ms. Indigestion instead. Cybil gets the role, and Simon sulkily settles for playing a jar of peanut butter. The teacher, Miss McFawn, wants Tony to play the dill pickle.

Simon sags with the discouragement of the troubles in his life: "Fathers desert you . . . friends lie about you, teachers humiliate you -- and those are supposed to be the good guys," and he remembers an expression of his father's, "Everythings's just gotten so damn complicated." But he ends up thinking of Cybil Ackerman with genuine appreciation: In the world that swirled in confusion and conflict around him, she was an oasis, a patch of fresh air, a circle of peace."

Many children will greet Ramona Quimby's return happily, as they would greet an old friend. All of her stories (see Bezus and Ramona, Ramona and Her Father, Ramona the Brave and other prequels) are notable for their humor and for the precision with which Beverly Cleary gets inside children, presenting their intense excitements, longings and traumas.

In Ramona Quimby, Age 8, our heroine has reached the third grde and like Simon Newton, she is havng some problems with her new teacher, Mrs. Whaley, who refers to her students as "you guys." On the first day of class, Ramona finds that her new sandals squeak. When Mrs. Whaley says, in front of the whole class, "We all know you have musical shoes," the class laughs at her. But Ramona responds with equanimity: "By walking with stiff legs and not bending her feet, Ramona reached her seat without squeaking at all. She did not know what to think. At first she thought Mrs. Whaley's remark was a reprimand, but then maybe her teacher was just trying to be funny. She couldn't tell about grown-ups sometimes. Ramona finally decided that any teacher who would let Yard Ape wear his baseball cap in the classroom wasn't really fussy about squeaking shoes."

Clearly fills her books with sensations that are redolent of real life. Who does not recall with Ramona the smell of a new soft Pink Pearl eraser? Who would not be shattered, as she is, to discover that radio cat food commercials may distort truth? The mirror held up to her life reflects sharply her disillusionments as well as the pleasures and vicissitudes of family life. Nowhere are more amusingly seen the efforts of daughters cooking Sunday dinner; nowhere are more sympathetically portrayed the languors of being sick with the flu.