Many government workers get a phone call every couple of months from Martha Brown, who's just checking to see if they're still there.

Brown spends up to six hours a day calling government telephones from her home in Silver Spring to help update the Federal Executive Directory, one of the commercial publications that sells information on the shifts of about 25,000 executive branch employes.

The directory contains a color-coded, cross-indexed listing of names, phone numbers and job titles, along with organizational charts and an alphabetical index of federal executives' names. It includes six updates a year for $96.

To keep track of those comings and goings, the Carroll Publishing Co., which puts out the directory, has five full-time researchers. The company also employs about a dozen part-time workers, including Brown, who call government offices from their homes to verify names and numbers, said company president Thomas E. Carroll.

"Occasionally some offices get a little bothered with us calling them, especially if somebody's already had a lot of calls that day," Brown said. "But I think they usually realize it's for their benefit, too."

The directory was first published in 1976. About 5,000 copies of it are sold annually.

The Federal Yellow Book, published by Washington Monitor, Inc., is a another directory which promises to keep up with who's who and where in the federal government. It, too, has been published since 1976 and about 7,000 copies a year are sold.

The Yellow Book comes in a loose-leaf binder and lists names, titles, addresses, offices and room numbers of federal executives.

The information is arranged to reflect the structure and organization of the agencies, "to help people wander through the maze of the federal bureaucracy," said managing editor Teri Calabrese.

A year's subscription costs $120 and includes updates every two months. At least a third of the directory must be revised each time, Calabrese said.

The toughest federal department to keep track of?

Carroll and Calabrese agree it's the Department of Energy, because of recent reorganizations.