Guide to Climatological Practices:
http://www.wmo.int/pages/prog/wcp/ccl/guide/documents/WMO_100_en.pdf
Guide to Hydrological Practices:
http://www.whycos.org/hwrp/guide/
Guide to Agricultural Meteorological Practices:
http://www.wmo.int/pages/prog/wcp/agm/gamp/gamp_en.php
= Guidelines on Analysis of extremes in a changing climate in support of informed decisions for adaptation:
http://eca.knmi.nl/documents/WCDMP_72_TD_1500_en_1.pdf