TY - JOUR TI - An Activity Model to Demonstrate Countercurrent Exchange JF - The American Biology Teacher DO - 10.2307/4450540 DA - 1998-09-01 UR - https://www.deepdyve.com/lp/crossref/an-activity-model-to-demonstrate-countercurrent-exchange-bDWVxmgD4k SP - 536 EP - 539 VL - 60 IS - 7 DP - DeepDyve ER -