S. Murthy  , R. Ramanarayanan  , 
    Two (s, S) Inventories with Perishable Units,
    Journal of Modern Mathematics and Statistics,
    Volume 2,Issue 3,
    2008,
    Pages 102-108,
    ISSN 1994-5388,
    jmmstat.2008.102.108,
    (https://makhillpublications.co/view-article.php?doi=jmmstat.2008.102.108)
    Abstract: Two  inventories A and B with maximum capacity S and with perishable items are considered. Inter occurrence times of demands and the lead time for order are random variables. Whenever the inventory level falls to s from S, order is made for <I>S - s</I> units to fill up inventories A or B or both as the case may be. Inventory level probabilities are presented for exponential distribution. Numerical examples are also presented.
    Keywords: Inventory systems;inventories in series;perishable units;renewal theory