81.   Terms of the agreement have been a closely guarded secret.

82.   Sterilization is the hard part, he explains, and the process is a closely guarded secret.

83.   The Air Force flew him to Bogota late Thursday, but his whereabouts were a closely guarded secret.

84.   The identity of the attorney directing the interview is a guarded secret.

85.   The identity of the new appointee has remained a closely guarded secret.

86.   The list has been a more closely guarded secret than the recipe for the drug Viagra.

87.   The rest is a closely guarded British military secret.

88.   Their operations were well guarded secrets even from those within the Taliban.

89.   The wedding, details of which have been a closely guarded secret, is to take place in Boston.

90.   They reportedly lived in various hotels, their locations a tightly guarded secret.