These links go to pages without a lot of math: 

https://www.boundless.com/finance/textbooks/boundless-finance-textbook/working-capital-management-18/inventory-management-129/seasonal-production-526-7969/

http://smallbusiness.chron.com/examples-seasonal-inventory-61418.html

http://www.hurlbutassociates.com/retail-perspectives-blog/bid/49251/How-To-Manage-Retail-Seasonality

https://www.involvation.nl/en/articles/sale-inventory-management-of-seasonal-products/

http://www.inventorymanagementreview.org/2005/06/what_to_do_abou.html

http://www.chainstoreage.com/article/dont-get-spooked-seasonal-inventory-management

Thanks for the help. Do you have any publications or books on this matter as well?

Hi Piet,

Are you interested in forecasting based on seasonal demand? If so, then you'd be interested in time series modeling approaches.

Ariel