Two or More Works by the Same Author in the Same Year: If you have two sources by the same author in the same year, use lower-case letters (a, b, c) with the year to order the entries in the reference list. Use the lower-case letters with the year in the in-text citation.
The next type of board is the longboard or malibu (mal). The main difference in design is that the nose of the longboard is rounded. Other than that there is no real difference, though shortboards tend to have three fins and longboards tend to have a single fin.
A surfboard, invented in ancient Hawaii, is an elongated platform used to support an individual standing on them while breaking a wave. They are made of polyurethane or polystyrene foam covered with layers of fiberglass cloth, and polyester or epoxy resin, making them light, strong, buoyant and maneuverable.